Sink or Swim

Do you need a great activity for teaching your kids or students about the scientific process? The Sink or Swim experiment is a fun way to help students develop skills in measurement, calculation and estimation. They will also learn about the concept of density while determining whether an object will sink or float.

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Density is defined as the amount of mass per unit of volume, i.e. the grams of mass per cubic centimeter of volume. Water has a density of 1.00 g/cm3. Objects that have a density greater than 1.00 g/cmwill sink, while objects that have a density less than 1.00 g/cmwill float.

The goal is to get a can to sit as low as possible in a container of water without sinking. Besides the container of water and some empty cans, all you need are a scale, some sand, and a ruler. Our Making YOU The Scientist video walks you through the steps to determine how much sand to add to the can to get the maximum possible density that will keep the can afloat. First you’ll need to determine the volume of the can and then the combined mass of the can and sand that is needed to get the selected density. Watch the video to get all the details on how to do the measurements and calculations.

You can find the instructions for this Sink or Swim experiment, along with some sample density calculation problems, in my TpT store. Turn this experiment into a challenge activity and give a prize to the person whose can floats lowest in the water.

Density measurements are used in the construction industry for calculating the distribution of weight for buildings, vessels, and other objects. The next time you’re planning a river trip, make sure you choose a raft or boat with the proper density to keep you afloat!


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