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STEM: Float and Sink Experiments for Preschoolers

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If you are unfamiliar with what STEM is, STEM stands for science, technology, engineering, and math. When you expose your preschooler to STEM activities and concepts at an early age, they will be more likely to succeed in those areas as they grow. Additionally, involving them in STEM activities might allow them to develop a love for science, technology, engineering, and math. Enjoying and having an interest in those topics will benefit your child’s educational pathway. This article will discuss STEM float and sink experiments that you can participate in with your child.

Recording Sheet

Before beginning all of your experiments, help your preschooler learn by creating a sink or float chart. To do this, draw three rows on a sheet of paper and make a column for every object you are testing the buoyancy of. Title the first row “What I Think Will Happen”, title the second row, “What I Tested”, and title the last row “Did it Sink or Float”.

After you create the chat, ask your child to guess if each item will sink or float and record their answers. Once that is complete, go throughout the activities and help your child write down which objects sink and which objects float. Not only will this help him remember the results of each experiment, but it can also serve as an educational tool for your child to review again if needed.

Tin Foil Boat and Pennies Exercise

The tin foil and pennies experiment is a great way to teach your preschooler about density, weight, and buoyancy.

To set up this exercise, you will need the following items:

  • Tin foil
  • Handful of pennies
  • A small to medium-sized container
  • Food coloring (optional)

Once you have gathered all the materials for the experiment, fill up the container with water. If you would like to make this activity more engaging for your preschooler, you can add a little drop of food coloring into the water.

After the water has been added, it is time to make your tin foil boats! With your child, create three or more boats out of tin foil in different designs. Some recommended styles are the bowl shape, square shape, or canoe shape. When your boats are complete, it is time to begin the educational activity.

Add a boat of your choice into the water and tell your preschooler to drop pennies into the boat. Count out loud how many pennies are added to the boat by your child until the boat sinks! Continue doing this with your other boat designs and see if some of the other shapes hold more pennies than the other boats did.

What Does This Experiment Teach?

The tin foil boat and pennies exercise teaches your child how added weight can affect an item’s ability to float. This is due to the increasing density of the boat and how the added mass causes the buoyancy of an object to decrease. It also educates your preschooler on the simple explanation of how boats float in water. When a boat is made, lots of math has to be done to ensure that the boat will float in water and not sink.

Small, Medium, and Large Item Sinking Test

The small, medium and large item sinking test can teach your child that size can be deceiving when considering if it will float or sink. Many preschoolers would assume that the smaller the item is, the more likely it is that it floats in water. To help teach them about mass, participate in this activity with your child.

To set up this activity, you will need the following items:

  • A marble ball
  • A ping pong ball
  • A golf ball
  • A foam pool noodle cut into a three-inch section
  • A medium-sized container
  • A Straw (optional)

In this experiment, the marble will be the small item tested, the ping pong ball and golf ball are the medium items tested, and the foam noodle will be the large item tested.

Before beginning the experiment, ask your child what they think will happen when each of the items is added to the water. Once recorded, it is time to start the activity.

To start, add the marble ball to the water. This will likely surprise your child because of its small size. Explain to your preschooler that the mass of the marble ball is heavy which causes it to sink and that an item being small does not mean that it will float.

Following the marble ball, give your child the two medium-sized objects, the ping pong ball, and the golf ball. Allow them to drop each in the water and watch as the ping pong ball floats and the golf ball sinks. This is another great way to explain the mass to your child because two objects can be the same size and have different densities.

Lastly, add the pool noodle to the water and allow it to float around. Your child has likely seen a pool noodle before and knows that it can float, but it may not know why. The density of a pool noodle is very low because of its sponge-like structure. This makes it easy for the noodle to float around without sinking in the water.

For additional enjoyment, give your child a plastic straw that they can use to blow the floating pool noodle and ping pong ball around the container. Using a straw can teach your child about kinetic energy, the energy an item has when it is moving. Just be sure that they do not drink the water with a straw.

What Do Children Learn From STEM Float and Sink Experiments?

Children learn many scientific and mathematical concepts when participating in float and sink experiments.

The first question that many children have when experimenting with floating objects is “what makes the object float?” This is a great opportunity to teach your child about buoyancy. Buoyancy tests an object’s ability to float in water. The more buoyant an object is, the more it floats above the water.

When children participate in these experiments, they learn what density is. Density is how much mass (weight) of an object is in each unit of volume. Density is used in math a lot and can be found by dividing the size of an object by its mass (weight).

Lastly, by allowing your child to play with floating items, they are learning about kinetic energy and how an object responds to being moved.

What Do Children Need to Know From STEM Float and Sink Experiments?

Not all objects can float, only objects that are less dense than water can float. While this may seem like common knowledge to adults, children need to grasp that if they throw something in the water that is too dense, that item will sink and they are likely to not see the item again.

To engage your child in more STEM activities, visit The Learning Experience’s Bubbles and Friends YouTube channel.

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