The Movement of Liquid Molecules

Objective: Students will observe food coloring being diluted in hot, room temperature, and cold water. Through this activity they will be able to visualize and better understand the concept of the constant motion of molecules.

Grade Level: 2-3

Duration: 20-30 min

Materials: *clear cups
                * hot, room temperature, and cold water
                * food coloring
                * milk
                * juice
                * soda

Procedure: Explain to students that everything is composed of molecules and that some objects' molecules move faster than others. Also explain that the faster the liquid molecules move, the faster it takes for the food coloring to dilute.

To demonstrate this, fill one clear cup with hot water, another with room temperature water, and the third with cold water.

Ask the class to predict which cup will change color completely the fastest. After the class has discussed it out loud, add a few drops of food coloring to each cup and have the class observe out loud what is going on.

After all of the liquids have changed color, ask the class which liquid took the fastest time to change color and discuss why this might have happened.

Separate the class into several groups and give them each a cup of juice, one of soda, and another of milk and have them pour several drops of food coloring and observe what happens. Ask them to guess which one they think will change color the fastest.

When they are done check for understanding by asking them based on the results of the milk, soda, and juice experiment, which of their molecules moved the fastest. (Remember that the faster the molecules move, the faster it takes for the food coloring to dilute.

Reference: www.canteach.ca/elementary/physical14.html

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