- Water bottle – glass is best but a STURDY plastic bottle can be used too (this will not work if you use a thin or flimsy bottle)
- Clear straw, white is OK if you can’t find clear
- Putty or playdough
- Rubbing alcohol
- Food dye
- Fill the water bottle about 1/4 way up with rubbing alcohol. Add an equal amount of water
- Add food coloring
- Place your straw into the bottle. Make sure the bottom is submerged but not all the way to the bottom and that the top is sticking out over the opening of the bottle.
- Use your putty or playdough to seal the straw in place. Keep the opening of the straw open to the air.
- Place your thermometer outside in the sun. As it warms the water mixture will rise up the straw… as it cools the mixture will recede