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Unit 18: Biology Part 1 Page 46 of 60

4. Blow up a balloon and start rubbing the side with your finger. This
sounds like the call of many frogs.
5. See if you can have a “conversation” with a frog.

What’s Happening: Frogs are amphibians, so they spend the first part of
their life in water. They live on the land as adults, but must return to the
water to reproduce. Male frogs “sing” to alert females to their presence and

encourage them to come into the water to reproduce.
Activity: Frog Egg Hunt

Once frogs lay eggs, they are generally fairly easy to spot in and around the
swamps and marshes in which they live. Each frog egg starts out as a tiny
dark spot surrounded by a thick layer of clear jelly-like stuff. The jelly acts

kind of like a shell that protects the egg. Most frogs' eggs form clumps.
This activity will work around April, when frogs lay their eggs.

1. Visit a local pond or swamp and seek out some frogs. Listen for frog

sounds and see if you can identify the type of frog.
2. Once you’ve found frogs, look for eggs.
3. Once you've found some eggs, make some observations. Are the eggs
floating at the surface or under the water? Are they attached to plants
or not? If they form a clump, is it small or large?
4. Come back again in a week or so. How do the eggs look different?

What’s Happening: Over time, the eggs will become larger and take on the
shape of the larva (tadpole, that will eventually be hatched from it.

Activity: Reptile Eggs

The type of egg you probably have the most familiarity with are chicken
eggs. Reptiles, like chickens and other birds, lay eggs. However, reptile
eggs are different in appearance and texture than chicken eggs, being more
leathery than smooth.

1. Place a chicken egg in a jar.
2. Cover the egg with vinegar and cover the jar.
3. Place the jar in the refrigerator and wait several days.
4. Remove the lid feel the egg making observations about texture.

What’s Happening: Vinegar is made of an acid called acetic acid. This acid

breaks down the calcium in the egg, making its texture very similar to the

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