Tub of Tears

Materials Needed
Activity
Career Connections
Assessment
Standards

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Did You Know?

• Buoyant is the word used to describe a material that floats in a liquid.
• Salt in water helps things to float better.
• Your tears are made of salt and water.

Materials: What You Will Need

• an assortment of materials with a range of buoyancy: For example: corks, wood blocks, feathers, foam, Styrofoam, nails, paper clips, buttons, spoons, clothespins, balls, sponges, small plastic bottles, film canisters, pipe cleaners, small plastic bowls
• large, clear plastic tubs for water
• containers for filling and emptying water tubs (i.e., plastic pitchers)
• fasteners, such as rubberbands, wire, twist-ties
• newspaper, to cover tables

To Get Ready:

Fill the tubs with water and put out all the various materials. You may want to use trays or bowls to keep the materials organized.

To Start, Ask:

What types of things float and what types of things sink in your bathtub or swimming pool?

Activity: Now, Try It!:

• Examine the assortment of objects at the table. What materials are they made of? Are some materials heavier than others? What shapes and sizes are they? Make predictions about which objects might float and which might sink when placed in a tub of water.
• Try placing different materials on the surface of the water. What happens?
• Try pushing the objects to the bottom of the tub of water. What happens when you release the objects?
• Can you separate the materials into groups that sink, float, or might do both?
• Imagine an animal or a creature that you might find floating on the water. Using the materials available, can you create a creature that will float? Try using an item that sinks for each item that floats. Can you combine floating and sinking objects to make your whole creature float?

Questions to Think about and Ask:

• Which materials seem to float easily? What do these floating items have in common?
• What materials sink easily? What do these sinking items have in common?
• What seems to be different between the floating materials and sinking materials?
• Does the shape of a material or object seem to affect how it sinks or floats?

Career Connection:

Oceanographers need to use buoyancy to move themselves and their equipment safely to and from the ocean floor. If they made a machine float too quickly to the surface, it could explode!

Assess What Happened: (Students reflect)

Ask students to think about objects that weren't available during their explorations that
might be used to create a floating creature. Write a paragraph that explains why they
would choose those objects to create a floating creature.

Connect It to the Story:

While in the Hall of Doors, Alice, who is a very tall girl, at this point, cries gallons of tears because she is so very frustrated from changing size so many times. Her frustrations are far from over because she drinks from a bottle and shrinks, landing in "the pool of tears which she had just wept when she was nine feet high." As she swims in her own tears, she meets a mouse and strikes up a conversation with him. Eventually, "the pool [became] quite crowded with the birds and animals that had fallen into it: there was a Duck and a Dodo, and a Lory and an Eaglet, and several other curious creatures. Alice led the way, and the whole party swam to shore." Can you make a curious creature that floats in a tub of tears?

Connect It to Standards:

In the physical sciences, students "should develop an understanding" that "objects have many observable properties, including size, weight, shape, ... and the ability to react with other substances" and that "objects can be described by the properties of the materials from which they are made, and those properties can be sued to separate or sort a group of objects or materials." (NSES Standards)