Hot or Cold: Which is Faster?

Content:  Changes that matter undergo Content Standards: Changes that material undergo when exposed to certain conditions Learning Competency: Describe changes in properties of materials when exposed to certain conditions such as temperature or when mixed without other materials.

              The primary purpose of this activity is to engage students in observing that hotter conditions can speed up changes in materials. Students will predict whether food coloring moves more quickly in hot, cold, or room temperature water. They then carry out a short activity to explore their predictions.

  Development of the lesson: The purpose of this activity is to let students observe the effect of heat on the movement of a drop of food coloring in water.

              Begin the activity by asking students to predict what will happen if they put a drop of food coloring into a small clear bottle with tap water. Then, place a drop of red (or any color) food coloring into a clear bottle filled with tap water and hold it up. Ask the children to describe what they see. Ask the students to observe the teacher demonstration on how food coloring moves into the water in a jar placed on top of the teacher’s table.

              Then, ask the students, “Do you think that the same thing would happen if we put food coloring into hot water? Or cold water? Would there be a difference? Let’s find out.”

              If students have difficulty answering this question, ask them to think about what happens when you make a cup of coffee in hot water. Or a more common drink for children is the use of powdered juice mixed in cold water.

              Next, students will conduct an activity in which they will drop food coloring into three small clear bottles with tap water, cold water, and hot water, and compare the speed (how fast or slow) of the movement of the food coloring in each bottle.

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