Activity 1

Make a thermometer

Materials you will need:
Glass bottle
Clay
Food coloring
2 deep pans hot water
cold water

Follow these directions:

1. Pour cold water into the bottle
2. Put a straw into the water about halfway
3. Mold the clay around the top of the bottle to make a tight seal.
4. Put the bottle into a deep pan
5. Pour hot tap water into the pan
6. Watch the water in the straw
7. Write a sentence about what you see happen
8. Put the bottle in cold water.

What happens?

 

Activity 2

When hot and cold meet

Materials:
A large jar or small aquarium
2 small bottles or baby food jars
red and blue food coloring
hot water
ice cold water
room temperature water
What happens when a small container of colored hot water and a small container of colored hot water is placed in a large container of room temperature water? Heat tends to move from warmer to cooler objects. In convection, heat moves by currents of pathways in a fluid. When a fluid such as water is heated it expands or tends to spread out, thus becoming lighter and less dense. In this activity, the hot colored water in the smaller jar is less dense and lighter than the surrounding cold water. The hot water is bouyed up or pushed upward by the cooler dense water. It rises and resembles smoke pouring from a chimney. The hot colored water tends to rise and then rest along the top or surface of the cooler water. If left long enough and the water is not disturbed, the colored water will cool and fall to the bottom of the tank. Mixture will occur as their temperature equalize. The ice cold water is denser than the surrounding water so it settles to the bottom.

Procedure:
Fill an aquarium with room temperature water. Fill the small bottle with hot water and add food coloring (3 drops) Cover the bottle with aluminum foil and put a rubber band around the neck. Gently lower the small bottle into the large container. Puncture a small hole in the aluminum foil so the colored hot water can flow out. A fountain of hot water will be released. Soon all the red water will be floating at the top. Students observe and draw the results on a worksheet.

Fill the other small bottle with very cold water. Place three drops of blue food coloring in it. Place into the large container. Puncture the foil top. Turn it on it's side. Students will record what they see. Why did the hot water rise to the top? Why did the very cold water stay on the bottom.

What happens when the temperature becomes the same throughout the container?

Students will conclude that hot water is lighter than room temperature water and cold water is the heaviest. As it cools down they all mix together.

Have them write what they learned about heat from this activity.

3rd Grade