Sink or float is one of the most popular classic science experiments for kids. It’s so easy to set up, and a great way to introduce them to basic experiments at home. This fun twist on the classic experiment uses surprise eggs to add another element of fun to the activity.

This sink or float surprise egg STEM activity was part of our #NickJrBlaze Twitter party. We’ve been trying out the new range of Blaze and the Monster Machines toys from Fisher Price, click the link to find out more about them.

Surprise egg sink or float experiment

For this surprise egg sink or float experiment you will need:

  • Bucket, filled with water.
  • Fillable plastic eggs (you can buy from craft stores)
  • A selection of small items of different weights.
  • Paper to note down guesses, and results.

It can also be handy to have a towel in case of water spillages.

For the surprise egg filler items, we used:

  • Cork
  • Small rocks
  • Polystyrene ball
  • Buttons
  • Paper clips
  • Plasticine

surprise egg sink or float

Fill each egg with a different type of items, and have the kids pick up and shake each one before dropping it into the water. They can guess what’s inside, and whether they think it will sink or float.

surprise egg sink or float

Once they’ve dropped it in, it’s time to see if they were right and find out what’s inside. They can note the answers down on paper too, to see what conclusions they can come to afterwards.

surprise egg sink or float experiment

We found that with the items being inside the surprise eggs, they can take slightly longer to sink than normal so at first the kids were shocked thinking that the heavy item was still going to float! But give it a couple of seconds, and they will sink as expected. Then the children commented about how the eggs were helping to keep the objects afloat.

sink or float with surprise eggs

To extend the activity, you can gather even more items and fill the surprise eggs with them to see what else will sink and float.

sink or float with plastic easter eggs

sink or float science experiment for kids

More Blaze inspired STEM activities

Measuring Vehicles Distances, STEM activity inspired by Blaze and the Monster Machines