Challenge the children to investigate these sensory floating and sinking bottles.
Early Learning Goal links
- Mathematics ELG: Numerical Patterns
- Understanding the World ELG: Past and Present
- Understanding the World ELG: People, Culture and Communities
- Understanding the World ELG: The Natural World
STEM vocabulary to introduce
Float, sink, sunk, sank, rise, rose, risen, size, big, small, heavy, light, bottom, top, surface, under
What to do
- Fill the bottles about three quarters full of water. Add food colouring if you wish to. Add a small amount of the material to be investigated. Put on the lid and secure with tape.
- Tell the children they are going to be marine engineers and will be curious about which materials float and which sink. You could show the children the marine engineer poster or use our sensory bottle provocation.
- Invite the children to investigate the bottles. Can they find out which bottles contain materials which sink and which contain materials which float?
Questions to ask to support and extend learning
- Is the material floating or sinking?
- Why do you think it is doing that?
What happens if….
- You turn the bottle upside down?
- On it’s side?
- You shake the bottle?
- You leave the bottle stood upright for a while?
- Is there a way to make the material sink?
- What would you like to put into a bottle?
Other things to try
- Remember to refer to the children as marine engineers and praise them for using the attributes. You could say things like: “You have been curious like a marine engineer and investigated whether the materials in the bottles float or sink…”
- You could investigate which liquids are more dense and sink to the bottom of the bottle or are less dense and float to the top of the bottle with the children.
- You could try tap water dyed with food colouring, oil, and sugar solution (sugar dissolved in water).
- What happens to each layer?
- What happens if you shake the bottle?
The science of floating and sinking
We have put together some useful information about the science of floating and sinking to accompany this activity. Don’t worry, this is for your information only and to help you answer any questions children may have. We don’t expect you to explain this to the children in your setting!
Why do some objects sink and other objects float?
There are two forces acting on objects in the water. The weight of the object pulls down, while the upthrust of the water pushes it up. If the weight of the object is equal to, or less than, the upthrust, it floats. Things that float are buoyant. If the weight of the object is greater than the upthrust, the object will sink.
What is upthrust?
This is the upward force pushing towards the surface. When you try to hold a beach ball, empty plastic bottle or inflatable under the water, you can feel this force pushing it towards the surface. The upthrust force is equal to the weight of water displaced by the object.
Why do some liquids float on top of others?
Density describes how much space an object or substance takes up (its volume) in relation to the amount of matter in that object or substance (its mass). More dense liquids, such as sugar solution or honey, will sink below less dense liquids, like water. Oil is less dense than water, so will float to the top.
What you’ll need
- Tough spot, trays or waterproof table
- Empty plastic bottles with lids
- Tape to secure the lids
- A variety of things to fill them with, such as:
- Food colouring
- A range of small objects that sink or float such as beads, lego blocks, cork, polystyrene beads, small pebbles
- Sensory floating and sinking bottles provocation
- The marine engineer poster
10 minutes preparation, 10 minutes or so for the activity.Marine Engineer poster