1. Activate students’ prior knowledge about big cat predators and their prey.
Discuss with students what they think of when they hear “big cats.” Ask: What pictures or words do you think of when I say "big cat"? What are some types of big cats that you can think of? Elicit from students that big cats include lions, tigers, leopards, cheetahs, and other large predatory cats. Distribute the worksheet Big Cats Tooth Comparison and have students examine the images of the skulls. Ask: What types of animals do you think these are? How do you know? Elicit from students that one is a human, one is a meat-eating lion, and the other is a plant-eating gazelle. Tell students to look at the differences in the shape and size of the animals’ teeth and jaws. Discuss their observations. Explain that in the wild, the lion is a predator and the gazelle is its prey. Ask: What is prey? Explain that prey are animals that are hunted and eaten by other animals. Ask: What are predators? Explain that predators are meat-eaters that feed on other animals. The shape and size of a lion’s teeth and jaws help it to be a successful predator.

2. Have students predict how their teeth and jaws compare to those of a lion.
Prompt students to list what they ate for breakfast or lunch. Write their responses on the board. Ask volunteers: Are you a meat-eater or a plant-eater? Elicit from students that most humans eat both plants and animals. Explain that an animal that eats a variety of organisms, including plants and animals, is an omnivore. Humans are omnivores so their mouths are designed to eat both meat and plants. Tell students that they are now going to make predictions about how their teeth and jaws compare to those of a lion. They will test their predictions by collecting more information. Read aloud the worksheet directions for Part 1: Prediction. Allow students time to make their predictions and complete Part 1.

3. Have students collect more information to test their predictions.
Divide students into small groups. Read aloud the worksheet directions for Part 2: Observations. Have students work in small groups and use mirrors to observe their teeth and mouths so they can sketch and describe the shape of their teeth. After students have sketched and described the shape of their front teeth (incisors), canine teeth, and back teeth (molars), have them measure the size of one group member’s canine teeth. Help them to correctly identify their canine teeth. Explain that if they find their two front teeth and go two teeth to the right or left, then they have found their canines. Then have students compare the size of human canine teeth to the size of lion canine teeth. Facilitate students as needed and encourage them to use the reference images provided on their worksheets.

4. Use the provided answer key to discuss students’ observations and predictions.
After students complete Part 2 of the worksheet, use the provided answer key to discuss their findings as a class. Ask students if their predictions were correct. Ask: Is a lion’s jaw bigger than a human’s? Are a lion’s teeth bigger than a human’s? Are all of the lion’s teeth the same shape? How does the shape of a human’s teeth compare to a lion’s? Elicit from students that the lion’s teeth and jaws are much larger than a human’s, but some of the shapes are similar. For example, humans and lions both have smaller, smoother front teeth (incisors) and sharp, pointed canine teeth. However, the shape of a human’s back teeth (molars) is quite different from a lion’s. Humans have back teeth that are rounded and bumpy, and lions have back teeth that are sharp. Ask students to compare the amount of teeth lions and humans have. Explain that adult lions have 30 teeth and adult humans have between 28 and 32. As kids, however, humans only have 20 teeth and they are temporary, or “baby” teeth. Ask students to compare the size (length) of their canine teeth to those of lions and adult humans. Adult lion canines are about 10 centimeters long and adult human canines are a little more than 1.5 centimeters long.

5. Have students reflect on similarities and differences between human and lion teeth.
Have students reflect on what they learned from their observations. Tell students to think about why human teeth are similar to and different from lion teeth. Have students share aloud the similarities and differences they observed. Facilitate the discussion. Ask: Why is the shape of a lion’s back teeth so different from a human’s? Elicit from students that the large size and sharp, pointed shape of a lion’s teeth are used to shred and tear the meat they eat. Humans’ flat, bumpy back teeth are used for grinding up food, especially plant material, such as vegetables, beans, and nuts. Ask: What teeth do we humans use to tear and eat meat? Elicit from students that we use our front teeth and canines to bite down and tear meat. Lions don’t need grinding teeth because they don’t really chew their food. They just tear it, break it into smaller chunks, and swallow it. Ask: How do the shape and size of the gazelle’s jaw and teeth help it eat? Students should be able to explain that the gazelle’s jaw is long and narrow and contains a lot of flat, bumpy teeth like human back teeth (molars). Ask: Based on this observation, can you predict what gazelles eat? Elicit from students that the gazelle’s teeth are flat and round, and therefore used for grinding up tough plant material like grass and shrubs. Students should understand that the shape and size of an animal’s teeth and jaw have evolved to help it eat specific types of plant and/or animal material.