Ask Ollie
Sink or Float Sorting Lab
Will it bob or will it drop? Test ten everyday things, then watch an orange do a surprising trick!
Reviewed by our team.
- Drowning risk around standing water; an adult must stay at the water the whole time
- Choking risk from small items such as coins
- Slippery floors from spilled water
- Citrus allergy or skin irritation from handling or peeling the orange
What you need
- Water, 1 large bowl or sink, filled
- Small waterproof toys (not for under 3s), a few, such as a toy car
- Paper, 2 sheets for SINK and FLOAT labels (optional)
- Crayons or markers, 1 (optional)
- Bowl, 1 large, or use the sink
- Towel, 1
- Household objects, about 10, such as a spoon and a cork
- Orange, 1 whole
How to do it
Grown-up prep: Fill a large bowl or the sink with water and lay a towel underneath to catch drips and keep the floor from getting slippery. Gather about ten small household objects, such as a spoon, a cork, a toy car, a leaf and a whole orange. Leave out coins and other tiny items for younger kids because they are a choking risk. If you do use them, keep them in your hand until it is their turn. Stay right at the water the whole time, since even shallow water can be a drowning risk. Skip the orange, or peel it yourself, if anyone has a citrus allergy or sensitive skin. Wash hands afterward.
- Fill the bowl or sink with water and lay a towel nearby. Ask for help if you need it
- Go on a hunt and collect ten small things from around the house.
- Make two piles or label two papers: SINK and FLOAT.
- Pick up one object and guess: will it sink or float?
- Gently place the object in the water and watch what happens. Ask: Was your guess right? Did anything surprise you?
- Take it out and sort it onto the SINK or FLOAT pile.
- Test the whole orange last. Most oranges float! Ask: Why do you think a big, heavy orange can float?
- Peel the orange together. A grown-up can start the peel with their fingers. Ask for help if you need it
- Put the peeled orange back in the water and watch.
- Now show your friends, or test more! What else will sink or float? Ask: What is the next thing you want to test?
Play it again
- Bath time lab: test bath toys and washcloths in the tub and sort them into sink and float.
- Boat builder: shape a lump of foil so it floats, then see how many small toys it can carry.
- Guess race: everyone guesses all ten objects first, then test them and count whose guesses were right.
Turn "I'm bored" into "let's do something together!" 3 free ideas a day, picked for your kids.