Grade
K

Math in Our World: Sink or Float?

A variety of objects in a bathtub filled with water.
Objects from the bathtub are sorted into 2 categories: sink or float. In the sink column: a whisk, a toy duck, a screw, a comb, a hand weight, toy binoculars, a necklace, scissors, a crayon, a rock, a die, a hard scrubbing pad, and a small piece of metal. In the float column: a feather, a Unifix cube, a pencil, a highlighter, a carabiner clip, a rubber bear, a toy magic wand, 2 refrigerator magnets, a small plastic counting square, a large plastic square, a chip clip, and a foam cylinder.

Today, we gathered items from around our home. We made predictions about whether each item would sink or float.

We filled the bathtub with a little water and then dropped each item in.

After we dried them off, we sorted them into groups.

  1. What do you notice? What do you wonder?
  2. Use pictures, numbers, or math words to show or tell about these pictures.
  3. What math questions can you ask about the pictures? Answer all the questions you can!
  • Make a table to sort and count the number of items that sank and floated.
  • Use tally marks to count how many of each category you see.
  • Show your work to someone else, and explain your thinking. Did they understand?
  • Ask whether they have any other questions you can answer!

You can do this experiment at home too! Gather small toys, items from outside, or things from the kitchen. Ask a grown-up to help you fill up a sink, the bathtub or a container with water. Count how many of your items sank and floated. Were you surprised by any of the items?

Printable Version

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Reference for Educators

Sample problems and solutions