Will It Sink or Float?

This simple sink or float science experiment is great for kids of all ages! It’s a fun way to work on making predictions, testing hypotheses and drawing conclusions. And, as a big bonus, it’s perfect for Valentine’s Day.

This post contains Amazon affiliate links.

Will It Sink or Float Fun science for kids. And it's perfect for Valentine's Day!

Getting Ready

To prep, I grabbed a bag of conversation hearts and seven clear glasses. Then I raided our pantry for every liquid I could find: apple juice, white vinegar, molasses, olive oil, water, maple syrup…

I printed off the free sink or float prediction sheet (below) and grabbed a pencil for Middle Brother to use when he filled it out.

Will the conversation hearts sink or float Fun science for kids!

Will It Sink or Float?

Middle Brother (age 4) LOVES science experiments so he was eager to jump in and start working. We filled each cup with a different liquid and labeled them with a strip of Scotch Expressions Tape.

Will the conversation hearts sink or float Fun Valentine's Day science for kids.

I helped him write down the name of each liquid on the chart. Then, focusing on one liquid at a time, he predicted whether the conversation heart he would drop in later was going to sink to the bottom or float on top. I marked his hypotheses with an X.

The most exciting part came next: finding out the results! We grabbed our cup of molasses, the first liquid on our list, and Middle Brother dropped in a conversation heart.

I love this sink or float kids' science experiment. So fun for Valentine's Day!

He was thrilled to see the heart plop on top of the sticky liquid and just float.

Will it sink or float Awesome conversation heart science for kids!

We marked the column “float” with a circle to show it was the actual result and talked about how it differed from his prediction (that the heart would sink).

Moving from one liquid to the next, Middle Brother continued testing his hypotheses and recording his results just like a grown up scientist.

The Science Behind It

Everything is made up of molecules – teeny tiny particles that can only be seen with a microscope.

If those molecules are packed very closely together they are more dense. If the molecules are spread apart, they are less dense.

Each of our liquids had a different density. When we dropped the conversation heart on top of a liquid, it would float on top if the liquid was more dense than the candy heart.

If, however, the liquid was less dense than the candy heart, it would sink to the bottom.

Ready to Experiment?!

Click the button below to grab your FREE sink or float record sheet and then hop over and continue the fun with our FREE conversation heart pattern strips!

Malia

Malia is a National Board Certified elementary teacher turned founder of Playdough to Plato and The STEM Laboratory - sites sharing addictively fun learning activities for kids. She earned her Master’s in Education from Stanford University and spent seven years teaching in a classroom.

Latest posts by Malia (see all)

Hi, I’m Malia.

I’m a National Board Certified Teacher and love showing Pre-K, Kindergarten and First Grade teachers easy-to-follow systems for getting EVERY student bigger results.