Sink & Float Displacement

Essential Question
What characteristics of a solid object determine whether it sinks or floats?

Objectives

 * Categorize objects whether they sink or float based on observed characteristics.
 * Interpret the results of the experiment and form new conclusions.

Introduction & Student Background
In this activity, students will use various objects to make a definition of what makes an object sink or float in water. They will measure the mass and volume to quanitify a characteristic, and then find the density by dividing mass by volume and find the correlation between density and sinking and floating.

Materials

 * Clear container of water
 * Large cubes
 * small cubes
 * balls
 * large cylinders of aluminum
 * small cylinders of aluminum
 * clear plastic
 * milky plastic
 * wood
 * Balances accurate to a gram
 * graduated cylinders
 * overflow jugs

PREP

 * 1) Put one of each of the items in a ziploc bag.
 * 2) Fill the clear tubs with tap water.
 * 3) Set out balances and graduated cylinders at each station.

ACTIVITY

 * 1) Give the students one of each of the objects (one ziploc bag per student)
 * 2) Separate the objects into a collection that would sink and a collection that would float. (2 Piles)
 * 3) Ask students what rule was used to decide how to divide these piles.
 * 4) Compare the mass and volume of each object and see if these measures determine whether it sinks or floats.
 * 5) Measure the mass of each object in grams with the balance.
 * 6) Measure the volume of the object in milliliters of displacement.
 * 7) What sinks and what floats? How does this change the students' definition? Have the students divide mass by volume (density).

How it Fits to Standard

 * The properties of an object depend on its shape and on the material it is made from.
 * Different kinds of materials display different properties.

Follow Up
What are some household objects you could try with this? Based on your new definition, which would sink and which would float?