Which is Heavier? A math experiment on weight

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If you’re looking for a fun and simple experiment using whatever objects your child can find around the house (and nothing more!), then this is one for you.

The Which is Heavier? math experiment uses household objects to help your child learn about weight and how to compare objects.

This foundational skill sets the stage for future math concepts and helps build critical thinking skills. So, grab a few household objects and get ready to have some fun exploring the world of weight!

which is heavier math experiment, teaching kids about weight, greater than, less than, and equal to

Supplies you will need

For this experiment, you will need the following:

Before you start

As long as your child is able to find objects of varying weights on their own, this is a great opportunity for them to take ownership of this experiment and choose their own objects to weigh.

If you’re noticing a lot of the objects are the same weight, you could have them choose one object and you choose the object to weigh it against.


Here is how to do the Which is Heavier? math experiment with your toddler:

Step 1: Introduce the concept of weight

Demonstrate the concept of weight by holding two objects with very different weights (a hollow ball and a rock in this image)

Before diving into the experiment, it’s important to explain to your child what weight means. You can say something like, “Weight is how heavy something is. The heavier something is, the more it weighs.”

You can also use familiar objects to demonstrate this concept (my preference!), like comparing a stuffed animal to a book.

Step 2 (Optional): Setting up the experiment with a balance scale

Using our balance scale to balance the weight of objects

This step is optional and depends on if you have (or want to makeOpens in a new tab.) a balance scale. I found a good deal on this balance scaleOpens in a new tab. and decided to purchase it.

If you don’t have a balance scale, don’t worry! This experiment can easily be done by just holding the objects and finding out which is heavier.

If you go that route, try to compare two objects that are very different in weight to help drive the idea home to your child.

Step 3: Making predictions

Now, it’s time to make a prediction. Ask your child which object they think is heavier and why they believe that. This will help them think critically and begin to understand the concept of weight.

If weight is a new topic for your child, you may have to talk through this first comparison together so they can understand the thought process. Then, once they have more confidence, allow them to take over.

Get your child involved: Have a conversation with your child about their thoughts on which is heavier, and ask a lot of open-ended questions like:

  • Why do you think the book is heavier than the teddy bear?
  • Can you think of other objects that are heavier or lighter than the objects we’re comparing?

Step 4: Conducting the experiment

Using a balance scale to balance objects

If you have a scale, use it to weigh the objects. Place one object on each side of the scale and ask your child to observe the numbers.

If you don’t have a scale, you can still compare the weight of the objects by holding one in each hand and asking your child to feel which one is heavier.

Step 5: Compare the weights

After weighing the objects, ask your child which object is heavier. If they predicted correctly, celebrate their achievement! If they were incorrect, encourage them to think about why they might have made that prediction and what they could do differently next time.

Ask them questions like:

  • How can we make the heavier object balance with the lighter object?
  • Can you think of something in our house that is even heavier than the heavy object?

To continue the experiment, you could do a play-off type game, where you find a lot of objects and try to find the heaviest by comparing two at a time!

The math behind the Which is Heavier? math experiment

This experiment teaches:

  • Comparisons
  • Understanding the concept of weight
  • Predicting an outcome

How it works

The Which is Heavier? math experiment starts the conversation with your child about comparing the weights of objects.

If your child is new to the concept of weight, this is a good experiment to introduce them to it. It’s a simple experiment that does not require a lot and is very easy to set up.


This experiment provides an opportunity for kids to compare and contrast two objects based on their weight. This can help them develop their critical thinking skills and also learn the concept of more than, equal to, and less than.

It’s especially helpful to compare objects that they enjoy and use often when starting out. This makes the math experiment more relatable to them, and therefore, more engaging!

Understanding weight

Weight can be a tough concept to grasp because it is less concrete than other mathematical concepts (like addition and subtraction).

By observing and weighing the objects, children can learn about weight and how it relates to the heaviness of an object. This can help them develop an understanding of basic math concepts such as measurement and comparison.

Predicting an outcome

This experiment provides an opportunity for kids to make predictions about which object is heavier before weighing them. This can help them learn how to make educated guesses and test their hypotheses.

We’re all home scientists here, so these are great skills to build when continuing your STEM home experiments.

More math experiments about comparisons to try out with your child

FAQ about the Which is Heavier? math experiment

How do you introduce the concept of weight?

Explain that weight is measuring how heavy or light an object is, and that everything has a weight (even something as light as a feather!). Start by comparing two objects that your child is interested in (like their favorite book and their pillow).

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