Workbook Pages

Key Ideas

• A species is a group of living things that can mate and have young, and whose young can also have young.
• Looking alike is a clue, not proof. Some species look almost identical, and some members of one species look nothing alike.
• Members of one species are never identical. Those differences are called variation, and they are normal.
• Breeds and varieties are groups people shaped inside a species. They never change what species a living thing is.
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• Species: A group of living things that can mate and produce young, and whose young can grow up and have young of their own.
• Offspring: The young that come from parents. Puppies, seedlings, chicks, and babies are all offspring.Interbreed: To mate and produce young together. Members of the same species can interbreed.
• Hybrid: The offspring of two different species, such as a mule. Most hybrids cannot have young of their own.
• Breed: A group within one animal species that people shaped on purpose, such as a beagle or a Great Dane.
• Variety: The same idea as a breed, used for plants. Honeycrisp and Granny Smith are varieties of apple.

1. Scientists find two fossil skeletons that look slightly different. They cannot watch the animals mate, because both died millions of years ago. How could they decide whether they were one species or two?
2. A group of birds gets blown out to an island and never meets the rest of its kind again. After thousands of years, how would you find out whether they are still the same species?
3. If every member of a species were exactly identical, what might happen to that species the first time a new disease came along?

• A ruler or tape measure, paper, and everyone in the house