While exploring in his yard, Sid finds two small bugs. “Hey there, rolie polies,” he says as he scoops them up. “Boy, you sure are small! Look! This one is rolled up into a ball, but that one is moving around. How are you doing that, little rolie polie?” “Mom, look! I found two rolie polies in the yard! But they’re so small it’s hard to tell how they move.” “That’s a good question, Sid. Let’s see what we can find out about how animals move on the computer. Here are some fish. They use their fins to move through the water. Snakes slide their bodies back and forth to move. And crabs use their claws to walk along the sand.” But Sid wants to know, “How do rolie polies move?” Mom suggests that Sid take his investigation to school. At school, Sid shows Gabriela, May, and Gerald his rolie polies. “Hi rolie polies!” says May. “Cool!” says Gabriela, checking out the bugs. “Wow! Wow! Wow! Look at ’em go! How do you think they move like that?” “That’s what I want to know!” “Teacher Susie, we have a question. How do rolie polies move?” “That’s a great question. Well, scientists, let’s think. Think of an animal you know, and then tell me how it moves.” “A cat is an animal! And cats have four legs for moving!” “A bird is an animal, and birds move by fluttering their wings to fly, like this!” “A rabbit is an animal! And rabbits jump. Watch me do it! Jump! Jump! Jump! That’s moving!” Everyone laughs. “A rolie polie is an animal!” Sid says when it’s his turn. “I see that rolie polies can move. But they’re too small. I can’t see how they move.” Gerald has an idea. “What if we invent a machine that makes things look bigger! Then we could see how rolie polies move!” “Well, Gerald, there’s already a science tool that does that. Does anyone know what it is?” They shake their heads no. “Is everyone ready to see a science tool that makes things look bigger?” Teacher Susie asks. “YES!” everyone shouts. “To the Super Fab Lab!” “Investigate! Explore! Discover!” “OK, here we go. The science tool that makes things bigger is . . . a magnifying glass!” “Whoa, cool!” Everyone takes a magnifying glass and looks through it. Using the magnifying glass makes really, really small things look REALLY, REALLY BIG. At last! Sid can get his answer. “Okay, magnifying glass. Do your thing!” Sid observes the bugs. “Wow! A rolie polie has two eyes, two loooong antennae, and look what else I can see! It has lots of little legs! Rolie polies have lots of little legs! Lots of little legs? Lots of little legs! That’s it! Rolie polies have lots of little legs! That’s how they move!” Just then, the rolie polie rolls into a ball, which makes Sid laugh. “When you do that, I can’t see your legs at all!” “OK, scientists! Draw your observations in your journals. What do things look like when they’re magnified?” After school Grandma picks Sid and Gabriela up. “Back seat driving with Grandma!” Sid sings, and Gabriela laughs. “So, tell me what you learned in school today!” Grandma asks. “Well, I wanted to know how rolie polies move, but they were too small for me to see,” Sid says. “So Teacher Susie gave us magnifying glasses.” “And I used my magnifying glass to see that rolie polies have lots of little legs. That’s how they move!” “Great work, scientists.” Grandma says proudly. “Maybe you can do some more magnification at home to see how other things move.” At home, everyone heads to the backyard. “Let’s investigate!” “I’m going to use my legs and move backwards to my chair,” says Grandma laughing. Sid and Gabriela look around the yard. “A butterfly! Look! It’s using its wings to fly.” Sid and Gabriela follow the butterfly to watch it land. Then Sid notices a caterpillar on the leaf near the butterfly. “A caterpillar! I wonder how that caterpillar moves.” Sid pulls out his magnifying glass to look at it. “A caterpillar has lots of legs, even more than a rolie polie! That’s how it moves.” Sid takes one last look at his rolie polies. He uses the magnifying glass to count their legs. “Fourteen,” he confirms. With the investigation complete, Sid lets the rolie polies go. “Goodbye rolie polies! Use those legs to move back home!”