This sink or float activity has kindergarten and 1st grade scientists predict and sort 12 picture cards on a Float and Sink mat, then circle new floating objects. Answer key included.
Will it sink or will it float?
Kindergartners don't need the word density yet, but they love the big question behind it: will it sink or float? They make a guess, drop an object in water, and watch what happens. Over time they notice that size alone doesn't decide it. A big wooden block floats, but a tiny metal paper clip sinks! They practice predicting, observing and sorting objects into two groups. The click comes when a child says, "I thought it would sink because it's big, but it floated!" That surprise is real science thinking.
Little scientists learn by guessing, testing and talking. These moves keep it simple and splashy.
Set out a tub of water and a basket of objects: a cork, a rock, a crayon, a spoon. Kids guess first, then drop each one in and sort it onto a "sink" or "float" mat. Hands in the water is where the learning happens.
Why it works: the U.S. Department of Education's guide for teaching elementary math recommends moving from hands-on objects to drawings to numbers.
Try it withSink or Float ActivityActivitiesOpen it →Hold up a new object and ask, "Sink or float?" Kids show a thumbs down for sink and thumbs up for float, then test it together. Predicting before every test keeps them thinking, not just splashing.
Why it works: pulling an answer out of memory makes it stick far better than rereading it, one of the strongest findings in learning research (Dunlosky and colleagues, 2013).
Leave the water tub out for a few days and add two new objects each morning. Kids keep testing during centers. Coming back to it again and again turns guesses into real patterns.
Why it works: short practice spread over several days beats one long session, according to a large review of learning research (Dunlosky and colleagues, 2013).
Water play is science play. Try these!
Keep it simple: some things are heavy for their size and sink, and some are light for their size and float. You don't need the word density yet. Let them test lots of objects and talk about what they notice.
Try corks, rocks, crayons, plastic spoons, coins, leaves, sponges, toy cars and apples. Mix big light things and small heavy things so kids see that size isn't the whole story.
Because floating depends on how heavy something is for its size, not just how big it is. A big piece of wood is light for its size, so it floats, while a small rock is heavy for its size and sinks.
Yes! The bathtub or kitchen sink works perfectly. Gather a few safe objects, ask your child to guess, then test together. It is a great five-minute science break.
Loved by 2 million teachers & families
Printables, songs and games for every subject, Preschool through 6th. Ready to teach today, and kids beg for more.
