When Maria was looking through books about birds, she noticed pictures of the Common Murre nesting on cliffs above the sea. Maria wondered why the birds' eggs didn't roll off the cliffs. She also wondered what the eggs were made of since they did not seem to break while resting on the hard rocky ledges.

Maria knew that egg shape and egg materials are like bird beaks - each special structure has a special job. In the activities of this experiment, you will study about bird eggs. At the end of your experiments, you will decide the best shape for eggs that rest on cliffs.

Bird eggs are not all the same.

A. The strength of a bird's egg depends on many things. Use an "X" to mark things that can make a bird's egg strong. You may mark more than one answer.

_______ The shape of the egg.

_______ The color of the egg.

_______ The material the shell is made of.

_______ The size of the egg.

_______ The thickness of the shell.

_______ The size of the yolk.

B. Choose ONE of the things you marked in question B and tell how you know it makes an egg strong.

Part A: How does the shape of an egg make a difference?

You will now experiment with model eggs to see which shape is best for rocky ledges. Take the cardboard ramp and three wooden eggs out of the bag.

STEP 1

Make an egg rolling ramp.

STEP 2

Place the ramp so it faces away from you. Clear your desk so there are no papers or materials near the ramp.

STEP 3

Set the egg on its side and roll it from the top of the ramp away from you onto the table.

STEP 4

Carefully watch how it rolls ON THE TABLE.

1. In the table below, draw a line that shows a path that each egg takes as it rolls on the table. For example, if the egg rolls straight after it leaves the cardboard ramp, you would draw a line like the sample below.

Be sure to roll ALL THREE eggs. Draw the paths below.

Sample Egg Roll

Draw a line that shows how Egg X rolls:

Draw a line that shows how Egg Y rolls:

Draw a line that shows how Egg Z rolls:

Egg Shape Observation

2. Complete the following table.

Egg	Describe the shape of the egg.	Describe in words how the egg rolled.

3. Does the shape of each egg make a difference in the way it rolls?

Explain your answer.

Sometimes it helps to look at the results of other people's experiments. Here are some drawings other students made of how each of the eggs rolled when released from the ramp.

4. After rolling the eggs and looking at the drawings of the other students above, which of the eggs do you think would be best for a bird that lays its eggs on a bare, rocky ledge? Why?

Part B: Are some shapes stronger than others?

Which shape would be the strongest?

To test this, Maria put blocks on top of 3 shapes until the weight made them break.

How many blocks to crush the shape?
Number of blocks needed to crush the shape	6 blocks	3 blocks	5 blocks

5. Does shape affect strength? Use the results of the strength tests shown above to explain which shape is strongest.

Part C: Does the material of an egg shell affect its strength?

STEP 1

Place 2 scoops of each powdered egg shell into different wells in the tray.

STEP 2

Add 5 drops of the Egg Shell Testing Solution.

6. Write down what you see happening in each well in the table below.

Egg Shell Test Obervations

Egg	What you saw when you added the drops

Part D: What can we conclude about the eggs?

8. Now you will compare the eggs to determine which one would be best for a bird that nests on a rocky cliff. For each of the rows or "tests" in the table below, give each egg a score for how good it would be on a rocky ledge.

good okay not so good

Test
How good was the egg on the ROLLING TEST?
How good was the egg on the STRENGTH TEST done by Maria?
How good was the egg on the MATERIAL TEST?

9. Which one of the three tests (A, B, or C) tells you the most important information about eggs that might be found on rocky cliffs? Why?

10. Based on the tests you did on the three eggs (X, Y, and Z), which egg would be the best for a bird that lives on a rocky ledge? Why?