Has your child ever questioned why they need a jacket one day, but a t-shirt is sufficient just a few days later? Or have they noticed it feels warm outside one day, and even warmer the next?

Explore with your child how temperature changes outside by creating a thermometer using a glass bottle and a few other household materials!

Find this activity along with other learning resources, parenting tips and more on pbs.org/parents.

Materials

• Empty glass bottle
• Measuring cup
• 1/2 cup water
• 1/2 cup rubbing alcohol
• Food coloring (color of your choice!)
• Clear straw
• Modeling clay
• Permanent marker

Directions

1. Start by asking your child to consider the weather. Ask, “How do we know what the temperature is outside? How do we know if it is cooler or warmer than yesterday?”
2. Pour the water into the glass bottle.
3. Pour the rubbing alcohol into the bottle. An adult should assist with this.
4. Add a few drops of food coloring. Mix by swirling the bottle around, gently.
5. Insert the straw into the bottle. The bottom of the straw should be within the colored water, but should not touch the bottom of the bottle.
6. Secure the straw with modeling clay at the top of the bottle. Make sure not to cover the top of the straw.
7. Place your thermometer in the sun and wait for a little while as the liquid rises.
8. Use the marker to draw a line on the outside of the bottle to show where the top of the liquid is in the straw. Write the date next to that line.
9. Ask your child about their observations: “Did the liquid in the thermometer rise after being in the sun? How long was the thermometer in the sun before you began to see the liquid rise? Did the liquid rise slowly or quickly?”
10. Use your thermometer in the same location at the same time each day for one week. Each time you check the thermometer, mark the level of the liquid and write the date with the marker. After collecting a few days of data, make some comparisons. Ask your child: “Is the temperature warmer or cooler than the last time you took it? Is the temperature warmer or cooler than the days earlier in the week? How can we use the thermometer to help us decide what to wear?”

Source: PBS KIDS for Parents. “Make a Bottle Thermometer.” Found at: pbs.org/parents/crafts-and-experiments/make-a-bottle-thermometer