The Toothpaste Experiment

The Toothpaste Experiment is a fun (though messy!) activity that’s perfect for exploring kindness with children. Before you start, why not explain to your child why kindness is important and how it can impact not only other people, but also ourselves?

  • Completing small acts of kindness can create a chemical reaction in our brains! When you do kind things, your body releases a chemical called oxytocin. This specific chemical helps to expand our blood vessels and reduces the risk of high blood pressure.
  • Being kind makes your brain produce more serotonin and dopamine, two neurotransmitters that help regulate your mood, and build pleasure in your brain.

If you’re a parent or carer, this is a great activity for demonstrating kindness in action with your child!


  • Full tube of toothpaste
  • Paper plates
  • Spoons

Once you’ve gathered your materials, get one person to empty the entire tube of toothpaste out onto the paper plate.

Beware – this experiment can get messy, so lay down a tablecloth or newspaper for easy clean-up!

Once they’ve done this, it’s now time to spoon the toothpaste back into the tube! Set a timer for 5 minutes to see how much you can get back into the tube with your hands. Take it in turns to see who gets the most in to the toothpaste tube – some of you will get more in than others.

Here are some questions you can ask your child whilst they try to fit the toothpaste into the tube:

  • How are you getting on?
  • How are you feeling trying to fit the toothpaste back into the tube?

Time’s Up!

Next, as your child what they think this has to do with kindness. Here’s a short explanation – share this with your child in whichever way you think best!

In this experiment, the toothpaste represents unkind words and actions. Once you’ve said or done something unkind it’s impossible to take it back. Once something has been said, it’s out there! Kindness is closely related to ‘self-control’: we need to think before we speak and consider the impact of our words on other people. Like the toothpaste, it doesn’t go back in easily!

We’d love to see you attempt this and what you learnt from doing this experiment. Make sure to tag us on social media and use #citywisescience, we’d love to know what you thought of this activity!