Field Trip Notes Liz is missing! The kids are worried, but Ms. Frizzle is calm. She knows Liz is at a spa for cold-blooded animals. To help the kids discover what it means to be cold-blooded, the Friz turns the class into reptiles, and they sneak inside Herp Haven. There, the kids are convinced that Ms. Herpst plans to harm Liz. They’ve got to save her! While trying to rescue Liz, the kids learn she has a different way of regulating her body temperature than warm-blooded animals - mammals and birds - do. One thing the kids don’t understand: Why doesn’t Liz want to leave Herp Haven?         Time: 20-30 minutes Group Size: One or two While trying to sink the bus, Ms. Frizzle’s class learns that shape and weight are two factors that determine whether an object floats. Your kids can change the shape - but not the weight - of clay balls so they float. Modeling clay (at art and toy stores) Several rolls of pennies Bucket filled with water Various objects: nuts, soap, fruit, vegetables, paper clips, jar lids Gather objects. Ask: Which do you think will float? Sink? Have kids test the objects and sort them into sinkers and floaters. Ask: What might make one object sink and another float? Drop a fist-sized clay ball into the bucket. It will sink. Ask: How can we make the clay float? Give each team a fist-sized clay ball. Ask: What will happen if you change the shape of the clay balls? How can you change your clay ball’s shape to make it float? Try it! Give each team a fist-sized clay ball. Ask: What will happen if you change the shape of the clay balls? How can you change your clay ball’s shape to make it float? Try it! Give each team 20 pennies and challenge them to change their boats so they’ll hold the most pennies. Ask: What happens as you add pennies? (Boats sink lower in water.) How can you change you boat to float more pennies? (Change the shape: Make the boat bigger and the sides higher, to push more water out of the way. High sides also keep water from swamping boats.) Time: 20 minutes Group Size: Two to four Ms. Frizzle’s class discovers three ways to raise sinkers. One way: to make an object lighter (so water can push up harder than the object pushes down). Another way is to change an object’s shape (so it can push more water out of the way for its weight). A third method is to attach lightweight “floaters” to an object (increasing its size without adding much weight, to help it push more water out of the way). Here, your kids can add “floaters” to raise sinkers. THE MYTH: Heavy things sink while light ones float. THE TRUTH: Weight is only part of it. The amount of space an object occupies - relative to its weight - is also important. A lead ball the same size as a Ping-Pong ball will sink, but pound that lead into a thin pancake and curl up the sides (same weight, different shape) and - voila! A floater! A tip from the Friz: Floating and sinking is a tough concept. Don’t expect neat answers from kids on why certain objects float and others sink. They’ll learn a lot by manipulating various objects. As kids explore, keep your focus on “What do you think would happen if...?” questions instead of “Why” questions. Bucket filled with water Masking tape String or garbage bag “twisties” Various sinkers: paper clips, spoons, marbles Balloons Ping-Pong balls Drop several sinkers into the bucket. Ask: How might you float a sinker? Show children Ping-Pong balls and marbles. Ask: What’s the difference? (Ping-Pong ball is larger but much lighter.) Drop them into bucket. (Ping-Pong ball floats; marble sinks.) Ask: How can you make the marble float? Encourage children to try different ways to get the sinkers to float. (Tape marble and Ping-Pong ball together; tie sinkers to blown-up balloons; make a paper clip “hook” and attach to balloon to help lift sinkers.) Ask: How do you think “floaters” helped? (increased object’s size and amount of water it pushes out of the way without adding much weight) Challenge students to make heavier sinkers float (two marbles, several paper clips).