Investigating Evaporation: Determine the variables that affect the rate of evaporation.

This activity is designed so that students are able to explain and demonstrate the process of evaporation. They should also discover the variables that affect the rate of evaporation i.e. surface area, heat, air movement, and water purity. They should experiment to see if they can increase the rate of evaporation. Their observation skills will be developed as they watch to see what happens to the dishes of water that are set out. The will use their writing skills in their science journals to explain the course of action that they took and the reasoning behind it. They will evaluate the results of their methods and explain why they did or did not work. Higher order thinking skills will be developed as they analyze the data from their experiments.
Vocabulary words for the lesson are as follows: evaporate, water vapor, variable, surface area.

This activity is for fourth grade, class size of 25, in an elementary school. It is based on observation and experiments done in the classroom. This is the lesson on evaporation, a process in the water cycle. It will take two days to complete this activity. Special equipment will be needed for their experiments i.e. hair dryer, paper fan, food coloring, salt, desk lamps, cups of water (one per group), wide shallow dishes, narrow deep dishes, sponge, water, overhead, overhead pen, any other items they would like to use in their experiment. This activity would be the second and third day of the water cycle unit. The students should be familiar with places to find water. This lesson will follow the introduction of the unit which will talk about where we find water, and the different kinds i.e. fresh and salt. I think it would be easy to adapt this activity to fit the needs of other classrooms.

Materials: wet sponge, chart paper, marker, ten dishes of water, five deep, five shallow, liquid watercolor paint, fan, refrigerator, prepared deck of cards

Whole group: Every Wednesday the janitors wash the chalkboard off with water. Is the water still there when we come to school Thursday morning? Let's see what happens if I wash the board with water. What do you think happens to the water? Have students write their own idea in their science journals first, then share ideas with the group.
Discuss as a group. Write their ideas on the board. Introduce evaporation if it has not yet been suggested. Write it on the board and have students write it in their science journals. Pose the question—Could we make this happen faster? Write down ideas.

Set up experiment. There are 2 dishes of water. How are they different? If we put exactly the same amount of water in each dish, what do you think will happen? Have a group of students set up these dishes. Will they evaporate at the same rate? Record their ideas. Leave overnight and observe the next day.

If I add something to the water, i.e. paint, what will happen? Have one group of students set up these dishes (matching the above dishes) with the same amount of liquid and paint as the first two. Do you think adding something to the water will affect the rate at which it evaporates? Will the paint evaporate too? Record their ideas. Observe the next day. 

What if a fan blows on these dishes of water? What do you think will happen? Students set this up and observe the next day.

What would happen if we put one shallow and one deep dish in the window in the sun and a shallow and deep dish in the refrigerator? Students set up and observe the next day.

Wherever water is stored, it evaporates.

Second day:
Whole group
Yesterday we came up with some ideas about what will affect evaporation. We also wrote down ideas about what would happen to the water in our containers. What did happen? Record results on chart paper from yesterday. What have we learned about evaporation? Surface area affects rate, water purity affects rate, air movement affects rate, temperature affects rate.
Choose a card from a prepared deck. Silently find the person with the same color and numeral i.e. 3 of spades and 3 of clubs. With that partner, write 3 examples of evaporation. Which example happened quickly and why? Write on a sheet of paper with both names and hand in.

We will use our knowledge about variables that affect the rate of evaporation. Each group will have a cup of water. Your group will try to find the fastest way to evaporate the water in your cup. You can use any of the objects on your table. (Not all of them will help you.) You may come up with ideas you would like to try. Measure the amount of water at the end of the day. As a class, discuss the results. Have the group with the least amount of water share their methods. Why did water evaporate quicker from their container? Review the variables. Write or draw about what you have learned about evaporation in your science journal. Label your drawings.

This activity was adapted from a unit by Kristy Brooten on the water cycle on lessonplanspage.com

I have not done this activity with students before. I think the safety issues would be having the electrical appliances near the water. That will have to be discussed.

This activity is different from what I have done in the past in that it is more hands-on. I would have set the experiments up by myself before. In this lesson the students will set up the experiments and take ownership of the lesson.

The students learning will be evaluated by reading in their science journals each day. The partner activity of listing three examples of evaporation and telling which one had the fastest rate will be handed in to the teacher to see if they can apply what they are learning. There will be a final group project of their choosing that will include all the processes in the water cycle. Each student will be assessed on the final product i.e. rap, skit, play, chart, sculpture, dance, song, story, mural, etc. There will also be a final test, multiple choice, that will be given.

4.III.B.1- Evaporation, process of water cycle