Investigating Evaporation: Determine the variables that affect the rate of evaporation.
In this lesson, students will observe water evaporating from the chalkboard after it has been washed. They will brainstorm what is happening and come up with evaporation. The students will then come up with ideas as to what would make this process happen quicker. Their ideas will be collected. They will test out their ideas using various materials. The students will compare the results from each group in the room. Each student will make a journal entry explaining what evaporation is and what variables affect its rate.
Vocabulary words for the lesson are as follows: evaporate, water vapor, variable, surface area.
Context for Use
Resource Type: Activities:Classroom Activity
Grade Level: Intermediate (3-5)
Theme: Teach the Earth:Teaching Environments:K12, Teach the Earth:Enhancing your Teaching:Problem Solving
Description and Teaching Materials
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.
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 http://www.lessonplanspage.com
Teaching Notes and Tips
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.