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Does It Float?

What makes an object float? What makes it sink? Explore the density of objects and liquids and make an ocean in a bottle!

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  • Do you want to do this adventure indoors, outdoors or at camp?
  • How will you clean up after this adventure?
  • How will you form your groups of five or six?
  • What do you think causes an object to sink? To float?


Activity #1: Does it sink or float?

  • In small teams, make predictions about which objects will sink or float. Why do you think some objects will float, and some will sink?
  • Test the objects once at a time. Were your predictions, right? Do you want to change any of your other predictions? Why?
  • What pattern do you notice among objects that sink vs. objects that float?

Activity #2: Make it float

  • What happens if you put an empty pop bottle and a bottle filled with sand in a bucket of water?
  • How can you make the bottle float just underneath the surface of the water?

Activity #3: Make an ocean in a bottle

  • Did you know that liquids can float on top of one another?
  • Fill a bottle halfway with water and add one or two drops of blue food colouring.
  • Fill up the bottle with cooking oil.
  • Shake the bottle. What do you notice?
  • Gently rock the bottle back and forth. What do you notice?


  • What do you know now that you did not know before?
  • What kinds of objects sink and what kinds of objects float in the water?
  • How did you solve the sand bottle challenge?
  • Why did the oil stay on top of the water?
  • What would happen if you added dish soap to your bottled ocean? Syrup?
  • How did you work together to make predictions?
  • What elements of STEM were in this Adventure? Science? Technology? Engineering? Mathematics?
  • What did you like about the Adventure? What did you not like about it?
  • How would you do this Adventure differently?


  • Bucket or tub of water for each small group
  • 10 objects that will sink or float. Examples include marbles, pieces of wood, small toys or light and heavy metal objects.
  • Plastic water or soda bottles (two for each participant)
  • Sand (enough for everyone to fill up their bottles)
  • Vegetable oil (enough for each person to fill their bottle half full)
  • Water
  • Blue food colouring

Keep it Simple

  • What happens when we throw garbage in the water? Why is it so important to keep our water clean! Learn about the importance of keeping our waterways clean!

Take it Further