Create Shade to Protect from the Sun

Background Information for Teachers

This section contains a quick review for teachers of the science and concepts covered in this lesson.

The Sun—the closest star to Earth—is essential for life on Earth. It is gigantic (more than 1 million times the volume of Earth), massive (about 330,000 times heavier than Earth) and, most importantly, is our main source of light and heat. Take the Sun away, and Earth would become a dark, frozen, lifeless ball floating around in space.

The light radiated by the Sun carries energy. When this light hits a surface, part of it gets absorbed and transformed into heat. This is why surfaces placed in the sun warm up. Once warmed up, these surfaces radiate heat. Earth's atmosphere retains and distributes this heat. This, together with the redistribution of heat by the oceans, keeps our planet at a temperature that supports life.

On a smaller scale, the warming of surfaces that receive direct sunlight can be uncomfortable or even dangerous. On a sunny day, a surface (e.g. rocks, soil, or concrete) in the sun can get extremely hot—too hot for some animals (like farm animals, cats, and dogs) and people. In the lesson How Sunlight Warms the Earth, students were taught that surfaces in the sun warm up. In this lesson, your students are challenged to protect a surface (an imaginary meadow) from this warming effect. They are given a variety of craft supplies including opaque and translucent materials. The key is to block visible light from reaching that surface. People and animals do this by seeking shelter from the sun in burrows or caves, under trees, under tents or umbrellas, or in buildings.

Additional Background Links

• 6 Creative Ways to Add Shade Outdoors, Elizabeth Lilly of ThisOldHouse.com
• Do I need to provide shade and shelter for my horse?, RSPCA
• Warm in the Sun, Science Buddies

Prep Work (5 minutes)

• In the days preceding the lesson, identify an area (preferably inside) where you will be leaving the cups in the sun. Whether you can do this depends on your geographic location, the time of year, and the orientation/size of windows in your classroom, as well as the weather. If you cannot get enough direct sunlight, then you can use a 60 watt or greater incandescent light bulb instead.
• Store the cups with soil, sand, or rocks in the shade and away from a direct heat source prior to the lesson.
• If students will craft their animal, craft an example animal.

Engage (10 minutes)

Show the students Figure 2, which is also included in the slideshow.

For students who participated in the lesson How Sunlight Warms the Earth:

Note: This lesson assumes students have learned that sunlight warms Earth's surface. If they did not learn this yet, this is a good place to explain it.

Sometimes, the sand gets so warm that it is uncomfortable to walk on. In this lesson, you will protect a space from getting so hot.

Explore (40 minutes)

1. Show Figure 3 or the third slide of the slideshow.
   
   
   Image Credit: Pixabay / Creative Commons Attribution 2.0 Generic license
   Figure 3. Horse in a meadow.

   Do you see the horse? The meadow can get very hot on a sunny day. The horse does not like that! Can you give the farmer ideas to keep the meadow cool?

   Listen to the students' ideas.

   We will not build a shelter for the horse in this picture, but we will create a small version to explain our ideas. Scientists call these models. Instead of a real horse, you will have your own animal like this one (show your example animal). Instead of a real meadow, you will get a cup with soil or rocks (show a cup half filled with soil or rocks). This is my animal in the meadow (show the example animal on the surface of the soil or rocks).

2. Allow students to craft their own toy animal or provide them with one. If students make their own animals, tell them the animal must fit in the cup, as shown in Figure 4.
   
   
   Image Credit: Sabine De Brabandere, Science Buddies / Science Buddies
   Figure 4. Example craft animals.
   
   
3. Divide the class in groups of 2 to 3 students.
4. Provide a cup to each student, and let them place their animal on the soil, sand, or rocks. Explain that the animal is now in the meadow, and students need to find a solution so that the sun cannot warm this space or the animal too much, even if their cups are placed in a sunny spot (show a sunny spot in the classroom). Show the materials they can use to find a solution.

In your groups, discuss how you can give your animal a space that the sun cannot warm too much, even if your cup is in the sun. You will need to move your cup around, so try to make it stable. Give each group some time to discuss before providing them with the materials to work with.

Give the groups craft materials. Encourage students within groups to share ideas and help each other. Make sure your students work in the shade and all cups are stored in the shade, away from any heat source.

Let the students construct their designs. Go around and ask students to explain the problem they are trying to solve and their ideas on how to solve it. Encourage students to identify why their idea will work. For example, if they build a tent from paper, it should work because the paper blocks sunlight, providing shade on the surface underneath it. Sunlight will not hit the surface, so it will not warm it up.

Ask students to draw their idea on the worksheet.

After they had time to draw, go over following checklist:

• Did you draw what is in the cup (soil, sand, or rocks)?
• Did you draw your construction or solution?

Some possible drawings are shown in Figure 5.

If students are ready early, allow them to decorate their construction and color their worksheet, or pair up groups that are ready and have them explain their constructions to each other.

Regroup the class and explain that they need to make sure their constructions solve the problem. To test, they will place the cups with the constructions in a sunny place. Discuss with your students the need to add a similar cup without a construction so, after some time, they can feel how the protected meadow feels compared to the unprotected meadow. Note that the animals are not in the construction during the testing, as the presence of the animal could obstruct the measurement.

Ask students to place their cups with the constructions in a sunny place. Add one extra cup of the same material (without protection from the sun). Make sure it stays in the sun so it can be reused by each group. Note that if students use different dry materials in their cups, you will need an extra cup for each material used.

After some time (at least 15 minutes if the sun is bright), allow each group, one by one, to feel if their construction solved the problem by touching the protected and unprotected meadows (touch the surface of the dirt/rocks/sand in both cups) and feeling if the protected meadow has an area that feels cooler.

Ask students to show their construction and announce their findings to the class.

Reflect (10 minutes)

Show the picture shown in Figure 1 (included in the slideshow) again.

Assess

Assess students' understanding from the explanations they provide for their solutions.