You will need
- Food colouring
- Sticky tape
- Something to protect surfaces (for example, newspaper or tablecloths)
- Clean, empty plastic bottles (500ml)
- Vegetable oil
- Clear hand wash
- A selection of different size and weight materials to fill the bottles (like shells, beads, scrabble letters, biodegradable glitter)
Before you begin
- You may want to run this experiment as one of a few bases. If you’re running two or three experiments at the same time, put the equipment each needs on the table and make sure there’s an adult at each table.
- Cover tables with newspaper or wipe down tablecloths – this could get messy!
- You can use baby oil instead of vegetable oil.
- It’s up to you what you put in the bottles. You could also try pebbles, paperclips, marbles, buttons, sweet wrappers, or Lego.
Prepare the bottles
- The person leading the experiment should give everyone a bottle. Everyone should use the jug to fill the bottle half full with water.
- Everyone should top up their bottle with handwash, vegetable oil, washing up liquid, or a mixture of them. They could also add some food colouring.
Fill the bottles
- Everyone should choose items to add to their bottle. They should try to choose things that are different shapes, sizes, and weights so they move at different speeds when they shake their bottle.
- Everyone should carefully drop or pour their chosen items in.
- Once everyone’s happy with their bottles, they should screw the lids on tightly. The person leading the experiment should help everyone make sure their lids are tight.
- Everyone should shake their bottle and watch how the different things inside mix, float, and sink.
This activity used a lot of skills (and some science) to create something that’s both beautiful and useful. Everyone should show each other their bottles and take some time to talk about how different people’s bottles are similar and different. What did people choose to fill their bottles with, and why did they choose those things? How did the different liquids affect the water? Oil is less dense than water, so however much people shake their bottles the oil will always try to rise to the top. Adding washing up liquid creates bubbles on top of the water, while hand wash usually creates bubbles within the water. What about food colouring? Did all the liquids change colour in the same way? Food colouring won’t mix with oil—if you see drops of colour in the oil, they’re trapped bubbles of water.
Everyone should shake and turn their bottles and follow the shapes inside. Which materials move the fastest and which move the slowest? What makes the items different? People may think about their shape, their size, what they’re made from, and how heavy they are. If everyone turns their bottles upside down, some items will probably sink straight to the bottom while others bob down slowly. Does anyone know why?
- Glue and solvents
Supervise young people appropriately when they’re using glue and solvent products. Make sure there’s plenty of ventilation. Be aware of any medical conditions which could be affected by glue or solvent use and make adjustments as needed.
- Rubbish and recycling
All items should be clean and suitable for this activity.
- Water games and activities
Be careful when doing activities with, in, or near water. Check surfaces and reduce the risk of slipping where possible. Make sure you have appropriate supervision for this activity.
Make it accessible
All Scout activities should be inclusive and accessible.