OBJECTIVES
Grades 5 – 8
°Become familiar with the microscope and its proper use.
°Prepare wet mount plant and animal slides.
°Observe prepared slides.
°Study diffusion and osmosis using dialysis tubing.
°Observe the stages of mitosis and understand that nuclear division is an important part of the cell cycle.

Grades 9-16
°Prepare slides and study the response of plants to changes in their osmotic environment.
°Examine a mite that is a normal inhabitant of human hair follicles.
°Observe stomates in the lower epidermis of a leaf and use counts of stomates in order to estimate the number in the entire leaf.
°Calculate the time needed for one cell cycle. The learner will understand cell growth and reproduction that occurs through mitosis and cytokinesis.

SCIENCE PROCESS SKILLS
Observing
Comparing
Inferring
Questioning
Applying
Hypothesizing
Collecting/Analyzing data
Logical thinking
Modeling
Writing scientifically
Designing an experiment
Forming conclusions

AAAS SCIENCE BENCHMARKS
5A Diversity of Life
5CCells
6CBasic Function

STATE SCIENCE CURRICULUM FRAMEWORKS
Grades 5 – 8
4.1.9Describe similarities/differences between single celled and multi- celled organisms.
4.1.10Explain how cells use food as a source of energy.
1.1.13Generate conclusions based on evidence.

Grades 9-12
2.1.15Analyze how scientific technology provides new tools for solving problems in all disciplines.
4.1.20Describe and explain the complexity of cellular structure and function (i.e., organelles, biochemistry, metabolism, photosynthesis, membrane functions, cell division).

SCIENCE EDUCATION STANDARDS (NCR)
Grades 5 – 8
Structure/Function in Living Systems
Reproduction and Heredity
Populations and Ecosystems
Diversity and Adaptations of Organisms

Grades 9-12
The Cell
HeredIty
Matter, Energy, Organization of Living Systems
Evolution of Living Systems
Biosphere and Interdependence

MATERIALS
Compound light microscope
Water source
Prepared animal and plant cell slides
Methylene blue stain
Toothpicks
Microscope slides
Covers lips
Droppers
Microscopes
Paper towels
Microscope immersion oil or mineral oil
Cardboard sheet or stiff index card
Oil of clove
Geranium plant leaves
15 cm plastic ruler
Dialysis tubing
20 cc syringe
15% glucose/2% starch solution
(15 grams of glucose, 2 grams of starch and 100 ml of water).
(This is enough solution for six groups.)
Iodine solution
(90 ml of water and 4 ml iodine)
Glucose testape
Plastic cups (large enough to hold 250 ml of water)
Triple beam balance
Salt solutions: 10% NaCl
Distilled water
Living Elodea leaves

KEY QUESTIONS
1.How are cells structured?
2.Explain how cells grow and divide.
3.What is the mechanism for cellular reproduction?
4.How do diffusion and osmosis differ?
5. What is dialysis?
Activity 1- Microscope use [The instructor should demonstrate as the students practice.]

Care of the Microscope
1.Carry the microscope in an upright position, one hand under the base, the other hand around the arm.
2.Do not permit excess electrical cord to dangle; leave some of the cord wrapped around the microscope.
3.Clean the lenses each time you use the microscope. Always use lens paper.
4.Report any difficulties with the microscope to the instructor.
5.Do not remove any part(s) of the microscope.
6.Do not allow the objective lens to strike the stage or slide/coverslip. 7.To store the microscope:
A.Turn nosepiece to the lowest power objective.
B.Wrap the cord around the microscope.
C.Cover.

Identification of Microscope Parts Using the table and the microscope diagram that follows, find and try out the various parts.
PartNameJob or Function
Aeyepiece/ocularholds top lens, usually lOx magnification through which object is viewed
Bbody tubesholds top lens, connects eyepiece to
objectives
Carmsupports body tube, a handle for carrying
Dnosepieceholds the objective lenses, turns to specific
objective
Ehigh powerobjective contains lens usually 40x, longest objective
on the nose iece, greatest detail
Fmedium power objectivecontains lens usually lOx, medium length if
3 objects are present, greater detail
Glow objectivecontains lens usually 4x, shortest length to
locate some detail
HCoarse adjustment moves body tube or stage up and down,
IFine adjustmentThe only adjustment used with high power.
JStageSupports the slide
Kstage clipsholds the slide in place
Ldiaphragm iris or diskcontrols the amount of light that enters the
microscope
Mlight sourceelectric lamp that provide the light into the
microscope
Nbasesupports the microscope, and used when
you carry the microscope
Ostage opening/apertureallows light to enter into the objectives

Use of the Microscope when using the microscope for the first time:
1.Turn on the microscope.
2.Look through the eyepiece. The cicle of light you see is called the field of view. Turn the diaphragm as you look through the eyepiece. You should notice that the light gets brighter or dimmer. Adjust the diaphragm with each specimen to determine the be st setting for that specimen.
3.Turn the nosepiece to change the objective lens. You should feel and/or hear a click as the objective is moved into place. Always start with the lowest power objective.
4.With a monocular microscope only one eye is used. Learn to work with both eyes open. If you have difficulty, hold your hand over one eye. It will be easiest to look through the microscope with your dominant eye.
5.The compound light microscope combines the magnifying power of two lenses. Total magnification equals the eyepiece magnification times the objective magnification. (eyepiece) x (objective) = total magnification. The eyepiece is usually lOX, the objectiv es are usually 4x, lOX, and 40X

The following procedure should always be used when observing any specimen under the microscope:

1.Start with the lowest power objective. Lower it as far as it will go.
2.Place the slide, prepared or temporary, on the stage. Be sure to use a cover slip.
3.Center your specimen over the stage- aperture. Raise the stage while looking through the eyepiece until you see the blurry image of the specimen.
4.Adjust the coarse focus, then fine tune with the fine focus. Remember to use the coarse focus only on low power.
5.Switch to medium power, adjust with the fine focus. Parfocal microscopes can switch directly from one objective to another without danger of hitting the slide.
6.Switch to high power, adjust the fine focus.

Making a temporary wet-mount slide (Figure 1)
1.Place a drop of water on a clean slide.
2.Place the specimen in the drop of water.
3.Position a cover slip at an angle over the specimen and gently lower into place.
4.Place slide on microscope stage and examine under low power.

Questions
a.why should you use a wet mount slide when viewing living cells?
b.why should the coverslip be lowered gently at an angle rather than being dropped on top of the specimen to be viewed?

Hints for Successful Microscope Observations
PROBLEMSOLUTION
Field of vision appears blackCheck to be sure that objective has clicked into position
Image appears fuzzy or unclearCheck eyepiece. Rotate it. Clean if
necessary.
Dirty eye iece or objectiveClean it.
Inability to locate specimenLower magnification. Recenter
specimen
Lack of sharp imageCheck to see that cover slip is on top
of slide
Too much or not enough light intensityAdjust diaphragm.
EyestrainObserve with both eyes open.
Out of focusAdjust focus frequently.
Inadequate observationScan all preparations by moving slide from side to side and up and down.

1.Place a drop of solution (stain, distilled, or salt water, etc.)
2.On the other side of the cover slip, put a piece of paper towel under the cover slip.
3.Allow the paper towel to draw the excess from under the cover slip.

Rules for microscope drawings
1.Pencil with shading or natural color with colored pencils.
2.Unlined paper, use one side only, leave at least a one inch margin on all sides.
3.Print all labels.
4.Three to four drawings per page maximum.
5.Draw and label only what you see through the microscope.

Pulling solutions across a wet-mount slide (Figure 2)
Activity 2- Cell observation

Materials
Paper towels
Coverslips
Eyedroppers
Microscope slides
Probes
Razor blades
Toothpicks
Unlined paper
Food coloring
Cork and/or bamboo
Methylene blue stain
Two or more colors of threads
Purple and yellow onion
Pencils and/or colored pencils
IKI/iodine stain
Assorted prepared slides such as:
Amoeba, paramecium, euglena, spirogyra, ulothrix, cholella, butterfly winds, insect eyes/mouth parts/legs, ox neuron, frog blood, etc.

Safety Considerations
°Breakage of glass slides and coverslips.
š IKI and methylene blue are toxins.
°Care should be taken in handling and using probes, razor blades, scissors, and toothpicks.
°Keep electrical connections dry and take care while plugging in or unplugging.

Procedures:
Make wet-mount slides of the following specimens. Observe them first on low power then on high power. Draw a representative cell on high power and label visible structures. Follow the directions given previously for making a wet-mount slide and for a dding solutions to a wet-mount slide.

1.Crossed Threads
Position two different colored threads (red, green) in an X on a clean slide. As you practice focusing note that because they are at different depths on your slide, both threads will not be in focus at the same time. This depth of field will also be n oticeable in cells viewed under the microscope.

2.Cork or Bamboo Cells
Shave a thin section from a piece of cork or bamboo, make a wet-mount slide and observe. A bottle cork, an old bamboo reed from a wind instrument, or fresh bamboo may be used. Note that in the dead cells, you will only see cell wall.

3.Onion Cells
Pull off the dry brown outer layer of a white or yellow onion and discard. Peel off a piece of the thin inner skin from between the thick layers of the onion and place it on a dean slide. Be careful to keep the tissue flat and in one layer. Put a drop of yellow food coloring or a drop of IKI (iodine) solution on the onion tissue. Wait a few seconds and blot the excess gently with a corner of paper towel. The cell and its structures will show up better after being stained. You should be able to see the cell wall, cytoplasm, and the nucleus. The cell membrane is directly inside the cell wall.
To see the cell membrane, compare fresh onion skin with onion skin that has been peeled off for around thirty minutes. The old onion will have dehydrated and the membrane and cytoplasm shrunk toward the center.

Questions
a.what differences do you notice between the unstained and stained slides?
b.what organelles, if any, can you see in the stained slide that you could not see in the unstained slide?

4.Purple onion
Repeat step three using a purple onion. Staining will not be necessary.

5.Cheek Cells
With the flat edge of a toothpick, gently rub the inside of your cheek. Smear the collected cell debris into a drop of water on a clean slide. Stain using methylene blue, iodine, or food coloring. You should be able to see the nucleus, cytoplasm, and cell membrane.

6.Stem Cross-Section
Slice as thin a section as possible from a fresh woody twig. Pace the section on a slide and observe it unstained, then stained with iodine, methylene blue or food coloring ring. Repeat with an herbaceous stem. You should be able to see various cells and tissue layers.

7.Prepared Slides
Observe various prepared slides (see materials list).

Typical Eukaryotic Cell Structures

Cell Parts

Nucleus
Nucleolus

Nuclear envelopes
pores
Chromosomes
Cell membrane

E.R.
smooth E.R
rough E.R.
Ribosomes
amino adds
Mitochondria
Vacuole
Vessicle
Lysosome
Golgi
Centriole

Microtubules
Chloroplast

Cell wall

Cytoplasm
Size (microns)

5-7
2

0.12-0.14
0.125
0.0024
0.006

0.01-0.08
0.01-0.08
0.01-0.08
0.025
0.0008
1.5-0.5
0.1
0.1
0.1
1-0.5
0.2-0.4

0.02-0.05
5.5-2

1-1.3

whole cell
Functions

šcommand center for cell activities and protein synthesis.
šproduces ribosomes and RNA
šregulateslates material entering and leaving nucleus.

šControls heredity
š controls materials entering and leaving cells
š lipid synthesis
šprotein synthesis
š protein synthesis
šbuilding blocks for protein
š cellular respiration produces energy from ATP

šstores water,minerals, food, waste

š membrane bound sac transports material

š garage collector in cell, cellular digestion

špackage material for export

šanimal cells only, microtubular organizing
center. i.e. Mitosis spindles and asters
šstructure and cytoplasmic streaming

š photosynthetic center of cell, contains chlorophyll. plant onl

šplant only, made cellulose
šmost cell activities occur
Activity 3
Observation of an animal living on the human skin: Follicle mites

Purpose
To examine a mite that is a normal inhabitant of human hair follicles.

Materials
Compound microscope
Two or more glass slides
Two or more glass cover slips
Toothpicks
Microscope immersion oil (or mineral oil)
A thin piece of cardboard (back of notepad, etc.)

Background Information
Animals come in all shapes and sizes. Some of the multicellular animals with complex and variously specialized organ systems are hardly larger than some of the one celled protozoans. Mites of the genus Demodex are closely related to the spiders and ticks, but are so small that they can live within the human hair follicle and feed on the follicular cells and the oils produced by the glands associated with the hair. The two species found on humans, D. folliculorum and D. brevis, do not commonly cause problems to their hosts, in fact, they are far less numerous in individuals with skin disorders such as acne. In some older people, D. folliculorum has been suspected of causing irritation and a reddening of the skin near the eye bro ws and lower forehead, painful but not severe. However, the related mite that occurs on dogs, D. canis, can cause demodectic mange, a rather severe skin condition. Numerous D. folliculorum may be found in a single follicle, but only one D. < I>brevis is found in an oil gland. Passage of mites from person to person is by direct contact.

Procedure

1.Clean a slide and cover slip. Place one drop of immersion oil or mineral oil onto the slide.

2.With one hand pull the skin of your forehead tight. Taking the card in the other hand press the edge of the card firmly against the skin and scrape it across your forehead. Remember, you are expressing oils and mites from the pores and follicles of the skin, so the firmer the pressure, the more likely you are to find mites. Best results are obtained by using the edge of a glass slide, but extreme care must be used to avoid breaking the slide and cutting yourself.

3.With the toothpick, remove the oily mass you have collected on your car and stir it into the drop of immersion oil on the slide. Place a cover slip over the drop.

4.Examine the slide under lOOX and change to 400X magnification when a suspected mite is observed. These mites are small, but easily seen under lOOX. The 400X is required only to examine the details of their structures.

5.It may be necessary to make more than one slide to determine how much pressure on the card is required to express the mites. However, everyone has some skin mites, so given patience, success should be virtually assured.

6.Good hunting!

To observe stomates in the lower epidermis of a leaf and to use stomatecounts under high power fields of view to estimate the total number in one leaf.

Activity 4- Gas exchange and photosynthesis

Purpose

Background Information
During photosynthesis CO2 and H2O are used as raw materials in the production of glucose. Light energy and enzymes are required in order for photosynthesis to occur. As water molecules are split providing electrons and H+ used in photosynthesis, oxyge n molecules are released. Most photosynthesis occurs in chIoroplasts in the mesophyll (middle) layers of the leaf. CO2 diffuses into the mesophyll region through stomata (small openings) in the leafs epidermal layers. Oxygen diffuses outward through th e stomates during photosynthesis. During periods of darkness with no photosynthesis and only cell respiration occurring, the direction of diffusion is reversed. Water diffuses into the mesophyll region from xylem cells in the veins providing a continuous flow of water from root hairs to the leaves. During any period when the stomates are open, water will diffuse outward from the leaf (transpiration). Opening and closing of stomata are controlled
In this activity, a portion of the lower epidermis will be removed from a leaf, and the stomates, with the surrounding guard cells, will be observed and counted. The total number of stomates in the lower epidermis of the entire leaf will be estimated from these counts.

Procedure
A.Number of Stomates
1. Tear a leaf at an angle while holding the lower surface upward. The tearing action should peel off a portion of the lower epidermis. It will appear as a narrow, colorless zone extending beyond the green part of the leaf.
2. Using forceps, tear off a small piece of this epidermis. immediately place it in a drop of water on a slide. Add a cover slip. Do not allow the fragment to dry out.
3. Using the low power objective of your microscope, locate some stomates. Then switch to the high-power objectives. Make a drawing to show the shape of a stomate, its guard cells, and a few adjacent cells in the epidermis.
4. Count the number of stomates in 5 high power fields of the microscope and average them. Calculate the average number of stomates per mm2 of leaf surface. This can be done by finding the diameter of the high power field of view and then computing the h igh power field of view area (area = r2). To find the high power diameter, divide the magnification number of the high power objective by that of the low power objective. Then divide the diameter of the low power field of view by this quotient. The resu lt is the diameter of the high power field of view.
5. Measure the total leaf surface area using cm2 grid paper and estimate the total number of stomates in the entire leaf.

Questions
1. What purpose do the guard cells serve?
2. What are the structures visible in the guard cells?
3. Why are there more stomates in the lower epidermis?
4. Can you think of a plant that would have more stomates in the upper epidermis than in the lower epidermis?
5. What plant types would be likely to have the fewest stomates?
Activity 5 – Diffusion and osmosis The life of a cell depends on movement of atoms and molecules. One of the results of this molecular motion is diffusion. Diffusion is the random movement of molecules from a place of higher concentration to a place of lower concentration. The concent ration of molecules at various points between the high and low areas forms a gradient, which is known as the concentration gradient.
Osmosis is the diffusion of water through a selectively permeable membrane. A selectively permeable membrane allows the diffusion of certain solutes and water molecules and restricts the movement of some solute molecules.
When comparing two solutions, the solution with the greater concentration of solutes is the hypertonic solution, while the solution with the lesser concentration of solutes is the hypotonic solution. when the two solutions are divided by a selectively per meable membrane, water molecules move from the hypotonic solution to the hypertonic solution. The solute molecules move from the hypertonic solution to the hypotonic solution. If the two solutions have the same concentrations of solutions are isotonic.

Background Information

Purpose
This activity is designed to observe diffusion and osmosis through a selectively permeable membrane (dialysis tubing). A selectively permeable membrane will allow substances to diffuse at different rates. The movement of a solute through a selectively permeable membrane is called dialysis.

Part A: Diffusion 1.Secretly place a drop of oil of clove in the front corner of the room.
2.Allow the aroma to diffuse through the room until students begin to notice the aroma and comment on it.

Procedure

Questions
1.What part of the room noticed the aroma first?
2.What part of the room noticed the aroma last?
3.Explain how the aroma moved through the room.
Part B: Dialysis

Procedure
All of the molecules of a given substance are about the same size, but the molecules of different substances are different in size. Iodine and water molecules are very small, glucose is larger and starch molecules are very large. A selectively permeable membrane allows some molecules to pass and restricts others. Design an experiment to show dialysis.

Materials
Dialysis tubing
20 cc syringe
15% glucose/2% starch solution
(15 grams of glucose, 2 grams of starch and 100 ml of water) (This is enough solution for six groups.)
Iodine solution (90 ml of water and 4 mi iodine)
glucose testtape
Plastic cups (large enough to hold 250 mL of water)
Water
Triple beam balance

Procedure
1.Using glucose testtape, test the glucose/starch solution. Record the results in the data table.
2.Cut a 30 cm length of dialysis tubing. Soak the tubing in a cup of water for five minutes. Remove the tubing from the water and tie one end.
3.Using the 20 cc syringe, place 15 ml of the glucose/starch in the dialysis bag. Tie the other end of the dialysis bag leaving enough space for expansion.
4.Record the color of the liquid in the bag in the data chart. Mass the bag and record the mass in the data table.
5.Mix 90 ml of water and 4 ml of iodine in a cup. Using glucose testtape, test the iodine solution and record the results in the data table.
6.Mass the cup and its contents. Record the mass in the data table.
7.Place the dialysis bag in iodine-water mixture and allow the setup to stand for thirty minutes. After thirty minutes, remove the dialysis bag from the iodine-water solution. Drain as much of the liquid as possible from the outside of the bag back into t he cup. Blot the dialysis bag dry on a paper towel. Mass the dialysis bag and record the results in the data chart.
8.Mass the cup and iodine solution. Record the results in the data chart.
9.Observe the color of the contents of the dialysis bag and the cup and record this information in the data table.
10.Using glucose testtape, test the liquid in the dialysis bag and in the cup and record the results in the data table.
11.Calculate the percent change in mass of the dialysis bag and of the cup (% Change in mass = (Final mass – Initial mass)/Initial Mass x 100).
Note:If water enters the bag, there will be a positive value for % change in mass. If water leaves the bag, there will be a negative change in mass. The same will be true for the cup.
DATA TABLE

InitialInitialFinal% ChangeFinal
ContentsColorMassTestapeColor
MassTestapeIn MassContents

Bag

Cup
Questions
1.Which substance(s) are entering the dialysis bag and which are leaving the bag? What evidence do you have to support this answer?
2.Which substance(s) did not pass through the membrane? Give supporting evidence for your answer.
3.Did water move in this experiment? What evidence do you have for the movement?
4.Referring to your experiment, were you correct? If you were incorrect, rewrite it to account for your observations.
5.Was the dialysis bag selectively permeable? Give evidence to support your answer.
6.Predict the effect of temperature on your experiment of…

Increasing the temperature:
Decreasing the temperature:
 To examine the response of plants to changes in their osmotic environment.

Activity 6- Membrane responses of living organisms

Purpose

Materials
Compound microscope
Slides and cover slips
Salt solutions 10% NaCl
Distilled water
Living Elodea leaves

Background Information:
In a healthy plant cell, isotonic with its environment, the cytoplasm, chIoroplasts, and other cell organelles are pressed against the rigid cell wall by a large central vacuole filled with water applying turgor pressure to the contents. The size of the central vacuole changes as water passes into or out of the cell in response to differing environmental conditions. when the plant is in a dry environment, the fluid outside the cell becomes more concentrated (hypertonic) than the cytopla sm, water passes out of the cell by osmosis, the vacuole becomes smaller, and the cytoplasm shrinks away from the cell wall. This process of cell shrinkage in plants is called plasmolysis. The combined shrinkage of all the plant’s cells cause it to appear wilted. when water is taken up by the plant, the fluids outside the cell become more dilute than the cytoplasm and water enters the cell, the vacuole increases in size, the cytoplasm becomes pressed against the cell wall by increased turgor pressu re, and the plant regains its unwilted shape. Since the central vacuole is the first cellular structure to gain or lose water, its size and effect on the positions of other cellular structures can be used as in indicator of the osmotic conditions with the plant cell.

Procedure
1.Make a temporary wet amount of an Elodea leaf using water from the plant’s container.
2.Cover with a cover slip and observe the distribution of cellular structures (chIoroplasts will be particularly visible) under low and then high power. Best results will be obtained in the thin area where the leaf was torn from the plant.
3.Place a drop of 10% salt solution on the side of the cover slip. On the other side of the cover slip, put a piece of paper towel under the cover slip (See Figure 2 in Activity 1). Allow the paper towel to draw the salt solution under the cover slip by c apillary action Observe the distribution of the chloroplasts as before. If no change occurs within a few minutes add another drop of 10% salt solution and draw it under the cover slip as before. Continue to observe the cells for up to 15 minutes.

Questions
1.Why do we use water from the plant’s container?
2.What changes would you expect to observe? what do you observe? Explain the results.
3.Is the 10% salt solution hypertonic or hypotonic to cellular contents?

Procedure
4.Place a drop of distilled water at the edge of the cover slip and draw it under the cover slip by capillary action, as before. Continue to add distilled water while observing the cells for changes in vacuole size for up to 15 minutes.

Questions
1.How is the salt concentration of the medium surrounding the leaf?
2.What do you expect to observe in the cells? what do you observe? Explain.

Activity 7- The cell cycle To identify cell cycle stages and estimate the time needed for one cell cycle.

Purpose

Background Information
The cell cycle includes both the period of time for the division of the nucleus (mitosis) and the period of time for cell growth and chromosome duplication. Interphase is the cell cycle stage between mitotic divisions during which cell growth and chromosome duplication occurs. Mitosis includes four cell cycle stages: prophase, metaphase, anaphase, and telophase. During prophase, the chromosomes become distinguishable as they condense. A spindle forms, and the nuclear membrane br eaks down. During metaphase, the chromosomes become arranged near the center of the cell. The chromatids of the chromosomes separate and move to opposite ends of the cell in anaphase. Cell division is completed in telophase as the cy toplasm divides (cytokinesis), the nuclear membrane reforms, and the two daughter cells separate.
Cell division in plants occurs in meristem tissue located in buds, cambium, and root tips. Of these regions of growth, the greatest number of dividing cells can be seen at the root tip. You will observe sections of Allium (onion) root tip. Toward t he main plant body the cells have grown to full length and are no longer dividing. Near the root tip, however, is the root apical meristem, a region of rapid cell division. Among the small cells of the root meristem you should be able to find cells in all stages of the cell cycle.
Unllke plants, which grow only in certain areas, animal growth occurs in various tissues throughout the body. Some cells in the human body are continuous replicators or are cell populations that continuously run the cell cycle. Examples of continuous repl icators would be skin, gastrointestinal lining, bone marrow, and hair follicles.
Some other cell types become incapable of continued cell division and are called non-replicators. Examples of these types of cells would be brain cells, heart muscle cells, and skeletal muscle cells.
A third class of cells are the occasional replicators. These cells normally do not undergo cell cycle but are capable if stimulated to do so. The most popular example of this kind of replicator is the liver cell. Liver cells normally do not divide. Howe ver, if part of the liver is surgically removed, the “stump” can regenerate the missing part by the re-initiation of the cell cycle in the “stump” liver cells. The cell cycle continues until there is complete replacement of what was surgically removed. As an animal matures, its rate of cell division declines; therefore, cell division is most common in embryos shortly after fertilization. For these observations, use a prepared slide of a whitefish blastula (a blastula is an early stage in development). A t this stage, the embryo is largely a mass of dividing cells. Four slices of about one hundred cells each were placed on each slide and stained. Among these sections you can find cells in all of the stages of the cell cycle.

Part A: Identification of the mitotic phases

Procedure

1.Using the Allium root tip slide, locate, sketch, and label cells in interphase, prophase, metaphase, anaphase, and telophase. Also notice the manner of cytokinesis, i.e., the formation of a new cell wall, called a cell plate, between the t wo new nuclei.
2.Using the whitefish blastula slide, locate, sketch, and label cells with nuclei in interphase, prophase, metaphase, anaphase, and telophase.

Part B: Calculation of cell cycle time
The chemical colchicine stops nuclear divisions at metaphase, but affects no other stage of the cell cycle. This can be used in attempts to determine the time needed for a full turn of the cell cycle. This can be used in attempts to determine t he time needed for a full turn of the cell cycle. First, the percentage of nuclei in metaphase of untreated tissue is determined (This value is about 1%). Living material is then treated for a specific time of 30 minutes (T) with colchicine. Slides of t he colchicine treated material are prepared, and again the percentage of metaphase nuclei is determined. The change in percentage over this specific time (T) relates to the overall time of the cell cycle as follows:

_____ % metaphase (colchicine treated cells)

_____-1% metaphase (normal cells)
=Q
T(time) = Q % of total cycle

Therefore, T/Q % = time of entire cell cycle

For example, if cells were treated for 30 minutes and (% treated) – (% normal) = 20%, then T/Q = 30 min/0.20 = 150 minutes for the entire cell cycle.

Procedure
1.The slides available in lab are of onion root tips treated for 30 minutes with colchicine. In normal tissue the percentage of nuclei in metaphase would be 1%. Two students work together, one as an observer and one as a recorder. The observer ranges up and down three central vertical rows of cells visible within the field at one time and identifies the cell cycle stage for each cell. The recorder records the data in the table below. Four such field counts should be made, with the observer and recorde r changing roles alter the second count. It is suggested that only the three most central rows be counted in each field.

Field Count

Phase1234Totals

prophase
_______________________________________________________________

metaphase
_______________________________________________________________

anaphase
_______________________________________________________________

telophase
_______________________________________________________________

interphase
_______________________________________________________________

Sum of all totals = ______ 2.Now divide the total of all metaphase cells by the total of all phases combined. This gives the percentage of 30 minute colchicine treated cells in metaphase. From this, subtract 1%, the percentage of untreated cells in metaphase. The normal length of the cell cycle can be calculated as shown above.

The length of the cell cycle for onion root tip cells is ___________

Ingredients

• 1 Junior Tech Rep from each 3rd and 4th grade homeroom class
• 3 Tech Reps (from previous year) to staff each computer lab
• 30 laminated or covered badges
• 1 Senior Tech Consultant (best problem-solver) from previous year cadre
• 1 Senior Tech Rep from each 5th grade class
• 30 rags for cleaning and dusting
• 2 bottles of cleaning solution (for outside of computer and desk area)
• Assorted computer parts for demonstration and student handling
• 3 large incentive charts (enough rows for each computer in the building)
• 1 clipboard for each Tech Rep

 Printer not working? Computer acting up? Need another pair of eyes? How would you like a technology specialist in every elementary intermediate classroom? If you answered yes to any of these questions, I have help. Over the past few years, I have used student Tech Reps who are trained to handle day-to-day technical problems, maintenance, and care of computers, printers, and peripherals. Included with this plan are our best practices which have been refined during the past three years. I am a half-time technology specialist and half-time gifted and talented resource teacher in a suburban Maryland elementary school of 540 pre-kindergarten through fifth grade students. We have 90 Ethernet (Power Macintosh, G3 or better) computers, ten printers, and assorted peripherals. How do I keep my sanity? Tech Reps to the rescue!

 This process begins late in the spring. Teachers in second, third, and fourth grades nominate students as next year’s Tech Reps. Each homeroom teacher (3-5) has at least one. Fifth graders are considered Senior Tech Reps. One fifth grade Tech Rep is also designated as a student Tech Rep Coordinator (this position is not announced, but naturally given to the best candidate). Students need only a positive outlook on technology and dedication to task to be considered for the position. Those who have been previous Tech Reps are promoted to Lab Tech Reps and help train the new classroom Reps.

 Academic success is not a primary consideration for inclusion–consistency is. Being a Tech Rep definitely has its rewards. The students’ outlook on school becomes extremely positive and can carry through their academic career. In fact, the best student Tech Reps I have had over the years are NOT generally the highest ability students. They are logical thinkers (big surprise) and learn kinesthetically.

 Students meet each Friday (or the last day of every week) from 8:30 to 9:00 a.m. This is usually DOL (Daily Oral Language–sentences are put on the board with errors in grammar or spelling and children correct them) or DEAR (Drop Everything And Read–sustained silent reading) time. Tech Rep curriculum is designed to foster growth of logical thinking and basic computer skills.

 Curriculum objectives include:

1. Logic
2. Identification of computer parts
3. Understanding the basic principles of hardware
4. Understanding the basic principles of software
5. Understanding the algorithm of troubleshooting
6. Making the connections
7. Preventive maintenance
8. Reporting of maintenance issues
9. Printers–paper jams and jamming in paper
10. Printing problems
11. Understanding the Internet
12. Troubleshooting software incompatibilities
13. Previewing and reviewing software

 Keeping Things Simple

Each student is given a badge, which serves as their pass and indicates their designated assigned computers. The front of the badge states the student’s name and title, while the reverse lists their homeroom teacher’s name as well as two other staff members’ names. The student is responsible for care of computers assigned to the listed staff.

 Students come in and check in on a large incentive chart. Teacher’s names are placed on the Y-axis of the chart, while dates and activities are logged on the X-axis. Students initial the correct box, while a Senior Tech Rep is responsible for passing out badges and making sure that they have the correct equipment for that day (usually a dusting and cleaning cloth). After arrival, we discuss previous issues that were solved. A short lecture and/or demonstration of an aspect of technology is explored and investigated.

 Then, the students then are sent to check in with their assigned teachers. Professionalism is stressed. Tech Reps introduce themselves, quickly explain to the teachers the day’s procedures, note any problems, and provide appropriate maintenance and troubleshooting. Students repeat this until their entire list (office staff also) have been serviced. As they return to my classroom, absent student Tech Rep badges are passed out to those who complete early to ensure complete school coverage. The charts are used to keep attendance information. Those who are unable to arrive at school on time are dropped (we have used the position to improve school attendance in a few instances.)

 Students should not be removed from the program unless they are unable to or choose not to complete the assigned technology tasks as given. Academic progress, completed homework, and behavior problems in the classroom are not a consideration. It is often that a Tech Rep’s behavior improves with this added responsibility. For some students, this is the only activity in which they are seen as “The Expert”. Needless to say, self-esteem is elevated greatly through this program.

 As students report back from their weekly visits, any problems are discussed (I make sure that my 5th grade Senior Tech Reps return first). Possible solutions are discussed, and occasionally both the junior and Senior Tech Reps go to remedy the problem. If the problem cannot be fixed, students log the trouble and date of instance on a white board in my room.

 Lessons I Learned

Start slow with the third graders. Their first two trips (in August/September) should be with a Senior Tech Rep. Use broken or outdated parts from the service center for educational purposes. Make badges attractive and professional-looking. The more the students feel like professionals, the more they act in a professional manner. Pair student and teacher’s personalities for the best match. Inform the staff of the date of service. Principals, teachers, counselors, and office staff need to close all sensitive files before service begins. Children do not lift computers or monitors–they will gather cords while I or another adult lifts the computer. This program was designed to foster growth of technology in the early grades.

 Wish List

I would like to have student Tech Reps report to school prior to the beginning of the school year for a few hours. They can then locate and go through initial training in a structured way without missing any academic time.

It can be an annoying experience going to a zoo and waiting for minutes on end to see an animal that you’re told is just hiding. But maybe it’s hiding for a reason. It hasn’t got anything to do with shyness either. It’s a simple fact that a lot of animals are nocturnal, and by their very nature, they just don’t like to be out and about during the daytime. When most other animals are asleep under the cover of darkness, these other animals come alive, and unfortunately seeing what they get up to is a bit of a mystery. That is, until now.

Night Safari at the Singapore Zoo proudly calls itself “the first wildlife park built to be viewed at night.” Officially opened in 1994, the exhibit took four years to plan and three years to construct – which is not surprising given that it’s set in 40 hectares of fairly dense secondary forest. By using subtle lighting, visitors can view about 100 species that like to go about their business at night. In fact, there are over 1,000 nocturnal animals that call the Night Safari home, so it’s not exactly a small experiment.

The birth of the Night Safari is a result of a combination of factors. The overwhelming response to night tours conducted at the Zoo in the late 1980s indicated a demand for wholesome night entertainment. Displaying tropical animals at night seemed ideal since 90% of them are nocturnal and therefore most active after dusk. Singapore’s predictable sunset at around 7.30pm and cool nights with little rainfall mean fewer operational problems for an outdoor night attraction.

Like the adjacent daytime zoo, the larger Night Safari grounds employs an ‘open concept’ design, where by the use of moats (both wet and dry) and effective camouflage, animals can be seen in their respective areas appearing as if they are roaming freely in the wilderness – everything from such rarely seen creatures as the slow loris or the fishing cats.

The Night Safari itself is divided into eight geographical zones representing the wildlife of Asia, Africa and South America. What’s more, there are three walking trails that make it feel like you’re exploring the dense jungle on foot, even though you’re just a visitor to a very special zoo. After all, it really does feel like a legitimate jungle. That might have something to do with the over 20,000 plants and 900 forest trees that makes up the background for these jungle animals.

What makes the zoo work so well, as a night time only experience, is the careful placement of lighting. The lighting is sufficient to clearly see the animals moving about (after you eyes have acclimatized to the dimness), but not bright enough that they won’t venture from A to B. According to the zoo, the effect is slightly stronger than natural moonlight.

If you’re lucky enough to be heading to Singapore any time soon, be sure to check it out. And rule out the morning or afternoon options. The doors are only open to the public from 7:30pm to midnight.

My investigative question was: Does the temperature of water affect the time it takes for the water to freeze?

Hypothesis

Materials

1. Water
2. 3 containers (similar)
3. Candy Thermometer (to measure temperature of water)
4. Watch (to measure time it takes for water to freeze)
5. Tablespoon (to measure the amount of water to put in the container)
6. Microwave (to heat water)
7. Freezer (to freeze water)

Research/Sources of Information

Before I start the experiment I need to find out:

• the temperature at which water freezes and boils
• the temperature of the freezer
• the room temperature
• the procedures and materials.

I also did the following experiment as background research.

1. I decided to use a clock timer to measure the time it takes for the water to freeze and a paper knife to feel if the water in the bottles has frozen and become solid ice.
2. I took four white glasses that were all the same kind.
3. I poured one cup of tap water into one glass and let it sit there so it could become room temperature water.
4. I used a different glass to make boiling water. I used one cup of water and I put it in the microwave to boil.
5. I had kept the water in the microwave for three minutes. When I had taken it out the water was boiling. Before I had put the water I had made a prediction that the water would turn into steam. When I took the water out it hadn’t turned into steam that showed that my prediction was wrong.
6. I was going to use a thermometer but then I realized that the thermometer was only for humans. The thermometer would only go high as 106 F and boiling water is 212 F.
7. Also, I realized that the timer I had picked won’t work because it goes down and I need one that goes up.
8. So I only put in two glasses of water in the refrigerator and I didn’t time them. This helped me identify the correct procedures and instruments to use in my experiment.

I used the book Science with water to help me identify the different temperatures at which water boils and freezes.

Vocabulary

The temperature of the water in four bottles at the start of the experiment is the manipulated variable. The time it takes for the water in the four bottles to freeze is the responding variable. The conditions of the experiment are the controlled variables. In my experiment, the controlled variables are:

1. the amount of water in the four bottles
2. the kind of bottles that are used
3. the temperature of the freezer.

Experiment

1. I took 3 bottles of the same kind and size.
2. I labeled the three bottles as #1, #2, #3.
3. In #1 I put one tablespoon of water. The temperature of the water was at room temperature.
4. In #2 I put one tablespoon of water. The temperature of the water was hot (130o F).
5. In #3 I put one tablespoon of water. The temperature of the water was very hot (200o F).
6. I placed the three bottles on a tray and put it on the top shelf of the freezer.
7. I noted the time it was 10:54 am. I set the stop-watch to beep every five minutes so I could check the bottle
   

   Results

   The following table shows the time at which the water in the three bottles froze on the top:

   Results

   Bottle #	Amount of Water	Temperature of Water	Time put in freezer	Time ice forms on top	Time taken to freeze
   #1	1 tablespoon	70 F (room temp)	10:54 am	11:45 am	51 minutes
   #2	1 tablespoon	135 F (hot)	10:54 am	12:00 pm	1 hour 14 minutes
   #3	1 tablespoon	200 F (very hot)	10:54 am	12:15 pm	1 hour 29 minutes

   These results can be shown in a graph like below:

   

   Conclusion

   The results of my experiment showed that temperature of water has an effect on the time it takes to freeze. My experiment proved my hypothesis – the higher the temperature of the water, the longer the time it takes for water to freeze – and showed that my hypothesis was correct.

   ---

   Optional

   How did I come up with my project idea?

   I picked it off the list of questions given by the school as the easiest experiment to do. I was not really interested in the effect of water temperature on freezing time. It might have been more interesting to see the effect of temperature on other liquids such as wine and oil.

   What did I learn from my experiment?

   I learned a lot of things. I have listed them below.

   How close were my hypothesis and conclusion?

   My hypothesis and conclusion were the same.

   Did I learn anything new from my project?

   Yes. I learned a lot of things in doing this experiment. They are:

   • I learnt how to be specific with my work
   • I learnt how to make a table
   • I learnt how to make a graph
   • I learnt to take pride in my work
   • I learnt to make a bar graph
   • I learnt to take my time.
   • I learnt how to use a thermometer.
   • I learnt how to read a thermometer.
   • I learnt to revise my work.
   • I learnt how to spell new words.
   • I think the scientific method is hard.

   What was the most interesting part of my project?

   Playing with the water and measuring the temperature.

Steps to Prepare a Science Fair Project

1. Select a Topic
Remember a Science Fair Project is a test you do to find an answer to a question, not just showing what you know about something. To find a effective topic/idea- look at sample projects, look at this list, look at projects in books or projects from last years science fair – then add your own question, your own idea to them.
Don’t just use these ideas.
Take these ideas and add something of your own.
For example, change Are dogs colorblind? to Are cats colorblind? Or look at another of the 5 senses of dogs and test their sense of taste…
• What material is the best insulator
• Are dogs colorblind
• Do soap bubbles last longer on warm or cold days
• Are hot air balloons different from blimps
• What is the best method, other than heat, to melt ice
• What effect does oil have on water plants
• What would happen to the weather if the Earth was a cube
• Do goldfish chemicals they sell you really help the fish adapt to the new aquarium
• How can a tomato plant be grafted to a potato plant How is sound obtained from a compact disk
• How does a nuclear reactor work, how does it look
• How is 2-yr old talk different from ours
• How does burning gasoline make a car move
• How do we tell how far away a star is from Earth
• What soils are best to build a house on
• How do plants react to different kinds of music, different light, colors, and different neighbor plants
• What is the best way to dispose of paper
• Do plants move
Ways to find a science fair project idea:
• Look at lists of science categories and pick one that you are interested in, then narrow that down to a project. (example, say you pick psychology, then narrow it to the differences between boys and girls, then to a topic like “Do boys remember boy-type pictures (footballs) better than girl-type pictures (flowers)?” (Two lists of categories attached)
• Use your experiences Remember a time you noticed something and thought “I wonder how that works?” or “I wonder what would happen if…” then turn that into a project. Check the science section of the school library. Browse and look at book titles, then look inside the ones that look interesting to you. Also thumb through encyclopedias and magazines. Good magazines for ideas are: National Geographic, Discover, Omni, Popular Science, Popular Mechanics, Mother Earth News, High Technology, Prevention, and Garbage. Perhaps go to the downtown Library.
• Think about current events. Look at the newspaper. People are hungry in Africa because of droughts – a project on growing plants without much rain, which types grow ok with little water? Or the ozone hole over Antarctica – how can we reduce ozone? -a project on non-aerosol ways to spray things. Or oil spills. how can we clean them up? -a project on how to clean oil out of water.
• Watch commercials on TV. Test their claims. Does that anti-perspirant really stop wetness better than other ones? What are the real differences between Barbie and imitation Barbie dolls? Can kids tell the difference between coke and Pepsi if they don’t know which they are drinking?

2. Gather Background Information
Gather information about your topic from books, magazines, the Internet, people and companies.
Keep notes about where you got your information.

3. Scientific Method
State the Purpose of your experiment – What are you trying to find out?
Select a variable (something you will change/vary) that will help you find your answer.
State your Hypothesis – your guess about what the answer will be.
Decide on and describe how you will change the thing you selected.
Decide on and describe how you will measure your results.

4. Run Controlled Experiment and Record Data
Do the experiment as described above.
Keep notes in one place. Write down everything you can think of, you might need it later.

5. Graphs and Charts
What happened? Answer that question, then put the results in graphs and charts.

6. Construct an Exhibit or Display
It has to be neat, but it does NOT have to be typed.
Make it fun, but be sure people can understand what you did.
Show that you used the Scientific Method.

7. Write a short Report
Tell the story of your project – tell what you did and exactly how you did it.
Include a page that shows where you gathered background information. It can be 2 pages or even more.
Using your notes you can make a first-class science fair project by writing a good paper explaining what you did. Some teachers/judges require less and others more, but you should consider following sections to write and organize your science fair project paper:
• Title Page: Your project’s name (it can be in the form of a question) Your name, school and grade.
• Table of Contents: List the parts of your report (Introduction, Hypothesis and Research, Procedure/Experiment, etc) and the page numbers where they begin. You’ll have to make this page after the others.
• Introduction: One paragraph that tells the whole story. One way to do this is to write a sentence for each idea in the scientific method. One of the purpose, one telling what experiment or test you did, etc.
• Hypothesis and Background Research: State your PURPOSE in more detail, what made you think of this project. Tell what you found out from the books or other sources you used to learn about your topic and be sure those sources are listed in your bibliography.
• Procedure/Experiment: List the materials you used and what you did. If drawings will make it clearer, draw on separate pages and put in this section. Explain in detail things you made.
• Results: Describe what happened, what you observed. Show your data.
• Conclusion: Describe your interpretation of your results. Look over your notes, charts, and log and write what you think your data shows. You can put your opinions here. Was your hypothesis (what you expected to happen) correct? Don’t be afraid to say that you might have made a mistake somewhere. Great discoveries can come from what we learn from mistakes!
Be sure to state the limitations of your project. (For example, if your project was to find out something about dogs and you used your dog, you can say “My dog did this. This might not be the same for other dogs.” You can’t say that all dogs would behave the same as yours because you didn’t check all dogs.)
• Credits/References: List of books, articles, pamphlets, people you talked to and any other sources you used for researching your idea and writing your paper.
• Sources: They are written or typed in this form:
Last name of author (or person you talked to), First name, “Title of article or chapter”, Title of source (book title , magazine title or “Conversation”), Place where published:Publisher name, Date, volume: pages.

8. Practice Presentation to Judges
Practice explaining your project to someone (parent, friend, grandparent, etc.) This will help you be calm on Science Fair Day. The judges are very nice and will be interested in what you did and what you learned.

9. Come to the Fair and have fun! See you there!



Objective
To learn about static electricity.

Materials
Two balloons, Tape, Two four-foot strings, and a Piece of dry wool cloth.

Procedure
Inflate the two large balloons and tie them to the ends of the strings. Hang these two balloons from the ceiling with a piece of tape. Adjust the length of the strings so that the balloons are barely touching each other. With the piece of wool cloth, rub each balloon for several seconds. What will happen when you let the balloons hang together freely? Will they pull together or farther apart?

Conclusion
The balloons are pushed away from each other as if there is a force there that can not be seen. This happens because each balloon has an electrical charge of static electricity. Because the charge of the electricity is the same on the surface of both the balloons, the balloons are repelled, or forced apart. Because the balloons are not very heavy, little charge is needed to separate them.

Objective
To learn about the characteristics of water.

Materials
Clear glass, and paper clips.

Procedure
Fill the glass with water until it is completely full. At this point you can predict, or guess, how many paper clips you will be able to put into the glass until the water over flows. Start placing the paper clips into the glass, but make sure you count them as you put them in. How many were you able to place in the glass before the water overflowed? How close was your guess?

Conclusion
If you guess a number from ten to twenty, you were far from the correct number. Once you tried it however, you realized that the cup of water could in fact hold hundreds of paper clips before it over flowed! This is because the water forms a thin skin around the water. Look at the glass of water from the side. You can see that the water is actually over the top of the glass. The layer of skin keeps the water from over flowing.

Theory:
A “Bell curve” is a Statistical term, which itself not a measure of anything. It is simply the representation of data that are common outcome of many sorts of statistical information. Roughly, a graph of results is a bell curve when there are many data points in the middle of the graph and fewer at the “edges.”

Introduction:
This is a very elementary level experiments  for students who have started taking lessons on Statistics. First reason I did this experiment is that I looked up “Bell Curve” and I wanted to know what it was and my mom thought it would be a good project.

Hypothesis :
If I drop the marbles in the center of the box then will they, because of gravity, fall around the middle of the boxes? Will each drop be the same, similar, or very different?

Materials :
A square of wood, 200 marbles,  plexi-glass, and wooden pegs are some of the main materials.

Procedure :
1. Build the box
2. Drop 200 marbles into the box
3. Record the results
4. Do it over 9 more times

Results / Conclusion:
My hypothesis was correct: the marbles did fall into the center of the box forming the bell curve.

Astronauts working in spacesuits to build the Space Station may get even colder than the suit designers imagined. Measuring the effects of extremely low temperatures on astronauts was the first step in making a better space suit.

Walking in spaceSpace suits must provide complete life support, safety, comfort, and mobility when astronaut leave the ship for up to 8.5 hours.Space suits therefore must provide compartments for the storage of food, water, oxygen, and waste, as well as protection from temperature extremes, vacuum, and micrometeoroids.

The suit, including gloves, boots, and helmet, contains many subsystems, each with a variety of sensors, transducers, and control elements. One area that needs improvement is the temperature inside the gloves.

The figure below shows the suit’s complexity.

Space Suit Design and Functions

1. First inner and outer liners of swimsuit fabric for comfort.
2. Next transport tubes for cooling and ventilation.
3. Third the pressure garment and its cover restraint.
4. Next layers of Mylar insulation, and a ripstop liner.
5. Outermost is the thermal micrometeoroid garment (TMG).

The general principle behind the space suit is that the astronaut’s body makes heat that is controlled by the life support system. If it gets to hot in the suit, either because the astronaut is working hard or in direct sunlight, the water cooling removes the heat. The reverse problem is when the astronaut can’t put enough heat into the space suit to stay warm.The lack of heat is felt first at the body’s extremities, notably the fingers tips. Boots can be heavily insulated to keep toes warm, but glove insulation is limited by the need for manual dexterity. Space walk efficiency can be adversely affected when astronauts’ hands become uncomfortably cold.To study the problem and improve glove design, NASA outfitted space suit gloves with tiny, battery-powered temperature loggers. The instrumented gloves were worn by astronauts Bernard Harris and Michael Foale during NASA’s STS63 mission flown by space shuttle Discovery.

HOBO Loggers mounted in glove
To monitor the temperature of the astronauts’ fingers, the gloves of the space suits were equipped with HOBO Littler temperature loggers. The units were secured between the outermost and insulation layers on the glove backs, out of the 100% oxygen environment of the glove interiors.

Four of the data loggers were connected via a cable 8-10 inches long to small thermistors sewn into the finger tips. A fifth HOBO measured the temperature on the back of the glove where the devices were placed.The data indicated that because the suits were being subjected to environments colder than their design limits, they were unable to keep the astronauts comfortable during the EVA if there were lulls in the astronauts’ metabolic rate. Rather than trying to further insulate the gloves, NASA engineers have decided to move to internal heaters for the finger tip areas.