Fill it Up! Teaching the basics of volume

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When introducing volume to a young child, it’s important to start with a basic introduction with hands-on activities guiding the learning.

This experiment shows how a controlled volume of water (1 cup) can look different in different-sized containers. It also allows your child to line up the containers by fill, sorting from “least full” to “fullest”.

We have a lesson on volume, pouring, and sorting all packed into one. Let’s get started!

How to make the Fill it Up! math experiment

Supplies you will need

For this experiment, you will need the following:

Before you start

This is an introduction to measuring the volume of liquid in an object for your child. Our goal for this experiment is to show how 1 cup of liquid can look different in different containers, as well as show what “half full”, “full”, and “empty” look like in different containers.

I would recommend having a towel under this experiment since you are pouring liquids from container to container.


Here is how to do the Fill it Up! math experiment with your toddler:

Step 1: Fill your pitcher up and add food coloring

We need at least 4 cups of water to do this experiment (more, if there are spills).

Fill up and add a few drops of food coloring. The food coloring is completely optional, but it does help to see the water and water levels easier in the containers.

Get your preschooler involved: Have your child pick out the color and add in the drops of food coloring to the pitcher water.

Step 2: Pour 1 cup of water from the pitcher into the measuring cup

Since the pitcher may be too heavy for them to begin pouring, it may be helpful to hold the weight of the pitcher and allow your child to carefully pour.

First, show your child where the measuring lines are on the measuring cup. Specifically, show them where the 1 cup line is and that that is our goal for pouring.

For the first pour, especially if they haven’t measured before, you will want to guide them to pour slowly and carefully to measure out exactly one cup.

Get your preschooler involved: Kids love pouring! You may need to guide them the first couple of times (especially with that heavy pitcher).

Step 3: Pour from the measuring cup into one container and repeat for all containers

Show your child how to carefully pour from the measuring cup into each container.

Ask them to make some observations about the containers. Is there a really full container and a container that doesn’t look as full?

Step 4: Line up containers according to fill levels

Once all of your containers are filled up, it’s time for your child to line them up from the container that is “least full” to the “fullest”.

In this step, we are having them sort the containers, which is a great math lesson in itself.

The math behind the Fill it Up! math experiment

This experiment teaches:

  • The beginning stages of measuring volume
  • An informal introduction to fractions
  • Lining up from the least amount to the most amount

How it works

Measuring, whether it’s measuring a height or a volume, is a math topic that can be explored even in very early childhood.

Since measuring using units and talking about the formal definition of volume is very advanced for young children, the actual act of measuring something (in non-standard units like with Unifix cubes for height or in simple terms like one cup) is what we are experimenting with in this activity.

The beginning stages of measuring volume

Children begin the process of learning measurement far before we think to teach it to them.

Children arrive at preschool with an everyday understanding of measurement that starts in infancy and develops throughout early childhood, often without adult assistance.

Linda M. Platas, San Francisco State UniversityOpens in a new tab.

The goal of this experiment is to organize our child’s knowledge of measurement to begin consciously applying units to things we measure.

By measuring out one cup of liquid, we are showing that any more or less is not exactly one cup. That is the volume of water that we are using for this experiment.

This is great practice for your child to pour in and measure the liquid in a measuring cup! It teaches them how to slowly pour (instead of getting wild with their pouring) and observe the amount in the measuring cup.

An informal introduction to fractions

Since your measuring cup likely has at least simple fractions on it, this is a great time to informally introduce fractions to your child.

Fractions are typically introduced at a basic level around grade 1 or 2, so showing simple fractions in a real-life scenario (like measuring out liquids) is a great introduction before it’s taught in school.

You can simply show a container as “half full” to give a visual to what a half looks like.

Lining up from least to most amount

Once each container has been filled with one cup of liquid, you should have 4 containers that are filled to different levels of the container itself.


Although we are using the same volume of water in each container, since the containers themselves are different sizes, they will have different levels of liquid in them.

This is a good opportunity to have your child line these containers up according to their fill levels (from “least full” to “most”).

Once they are lined up, you can show how one cup of liquid in each container can look different, depending on the size of the container.

More measuring math experiments to try out with your child

FAQ about the Fill it Up! math experiment

How do you explain volume to a preschooler?

Explaining volume to a preschooler is best taught through hands-on activities with containers and a measuring cup. This experiment is a basic introduction to how a specific volume of water (one cup, in this case) can look different in different-sized containers. If the controlled volume of water fills container 1 and not container 2, then the volume of container 1 is less than the volume of container 2.

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