Bottle Thermometer
Track how the sun changes the temperature in a room
Materials
Plastic bottle
Clear straw
Rubbing alcohol
Red food coloring
Small cup
Balloon
Scissors
Rubber band
Pipette
Permanent marker
2 bowls
Ice water & hot water
Directions
Fill the bottle a little more than halfway with rubbing alcohol. Then, drip a few drops of red food coloring into the bottle and swish it around until it’s well mixed.
Pour a little bit of the alcohol out of the bottle and into the small cup. Set aside the cup.
Cut the neck off of the balloon. Then, stretch the other end of the balloon over the top of the bottle and secure it with the rubber band.
Cut a very small slit in the middle of the balloon. Then, insert the straw into the slit and gently push it into the bottle until just the tip of the straw is submerged in the alcohol.
Use the pipette to drip the alcohol from the cup into the straw. The alcohol should stay in the straw. Keep adding alcohol until the alcohol level reaches about ⅓ of the way up the exposed part of the straw.
Calibrate your thermometer! Place the bottle in a bowl of ice water and let it sit for about 5 minutes. Then, mark the level of the alcohol on the straw with a permanent marker.
adapted from Kiwi Co