Sink or Float Lab

About Sink or Float Lab

Pibbit the robot holds up something from around the house, an apple, a key or a big pumpkin, and your child decides: will it float or sink? They put it on the Float shelf or the Sink shelf, then drop it in the bath and watch. The coin plunges, the grape drifts down slowly, the ice cube floats with most of it hidden under the water. Six experiments build up to the tricky ones: an orange that floats until you peel it, clay that sinks as a ball but floats as a boat, and an egg that rises when you stir salt into the water. A wrong guess isn't a mistake here. Pibbit calls it a surprise, and explains what happened.

Sink or Float Lab is one of our free science & nature games for kids — play it right here in your browser, or browse all our free online games. It is also in our games for toddlers and preschoolers collection.

How to Play

• Listen to Pibbit's question, then drag the object to the Float shelf or the Sink shelf. Tapping a shelf works too.
• Drag it from the shelf into the bath tub, or tap the tub, and watch what it does.
• A star means you guessed right. A light bulb means a surprise, and Pibbit tells you why it happened.
• In the later experiments, squash and pinch the clay into a boat, load it with marbles, and shake salt into the water.

Tips & Tricks

• Before each drop, ask out loud why they think it will float. The reason matters more than the guess.
• Watch how fast things sink. A coin drops straight down, a grape takes its time. Both sink, but the coin is much heavier for its size.
• Poke a floating object in the tub. It bobs straight back up.

What Kids Learn

Sink or Float Lab follows the same loop science lessons use: guess first, test it, then talk about what happened. Every object starts with a prediction on a shelf, every result goes onto a small chart with a star or a light bulb, and the end of the game shows the whole lab report. Children who are used to quizzes are often surprised that a wrong guess still earns something. Here it's the most interesting part.

The objects are chosen to break the idea most young children start with, that heavy things sink and light things float. A big pumpkin floats while a tiny grape sinks, an orange floats until its peel comes off, and the same lump of clay sinks as a ball but floats as a boat. By the end, the idea Pibbit keeps coming back to is the right one: it's about how heavy something is for its size. Each object behaves the way the real thing does, and the ice cube floats with about nine tenths of it under the water, just as ice really does.

• Making a prediction, testing it and recording the result
• Learning that size alone doesn't decide whether something floats
• Seeing how shape (a clay boat) and salty water change floating

Curriculum links

For teachers and homeschooling parents, here is where Sink or Float Lab lines up with what children are taught at school:

• NGSS 2-PS1-1: Describe and classify materials by their observable properties
• NGSS K-2-ETS1-1: Ask questions and make observations to find out how something works

What Age Is Sink or Float Lab For?

Made for ages 3 to 8. Three- and four-year-olds can play by ear: Pibbit asks every question out loud and nothing can go wrong, so they can just enjoy the splash. Five- to eight-year-olds get more from the later experiments, especially loading the clay boat with marbles and making an egg float with salt. It's a good one to play side by side and argue about the guesses.

Tips for Parents

Do one of the experiments for real afterwards: an orange in a bowl of water, then the same orange peeled.

When they guess wrong, ask what surprised them. Changing your mind because of evidence is the skill this game is really about.

Try the salt one in a tall glass. You'll need a lot more salt than you think, which is a good lesson in itself.

Try It Without a Screen

• Fill the sink and test five things from the kitchen drawer. Guess first, and keep score on a scrap of paper.
• Make a boat from a square of foil and count how many coins it holds before it sinks.
• Put a fresh egg in a glass of water, then stir in salt a spoonful at a time until it rises.

Sink or Float Lab — Frequently Asked Questions