GO IN DEPTH

Measuring Cloud Coverage

Materials

• Poster paper (at least two pieces)
• Graph paper

Purpose

To review what clouds are and then use fractions to describe cloud coverage.

Context

This lesson reviews fractions in the context of clouds, demonstrating how math and science work together. By using math and science to describe clouds, the lesson gives students several means of communication (fractions and meteorological terms) to describe a meteorological situation. Whereas a student may have looked up at the sky before the lesson and said there are a lot of clouds in the sky, after the lesson, the student may look up and think that not only are there a lot of clouds in the sky, but also that it is about 90 percent covered and/or that it is overcast.

The motivation exercise asks students to make observations of the sky. Then, the first part of the lesson is a quick review of what clouds are made of and how they form. This moves into the next part of the lesson, which uses fractions to describe cloud coverage.

Students at this grade level will likely be quite familiar with clouds. Even if they aren't familiar with the specific types of clouds, they should have learned in K-2 about water condensation and the water cycle. They should have the base knowledge that clouds are made of water. This basic understanding of clouds is necessary for the lesson.

Students also should have a basic understanding of fractions in order to do this lesson. You will have to gauge whether or not your students are at the right stage for fractions. Obviously, fifth graders will be ready, but third graders may or may not be.

According to research, elementary- and middle-school students make several errors when they operate on decimals and fractions because "they lack essential concepts about decimals and fractions and have memorized procedures that they apply incorrectly." Examples of mistakes that students may make, such as multiplying and dividing, are not related directly to this lesson. The lesson will emphasize, however, the very basics of what a fraction is and therefore may help in establishing a good base knowledge in this area of math.

Motivation

As an introduction to the lesson, start a brainstorming discussion. Ask students:

• Look at the sky and describe it.
(Write what they say on a large piece of poster paper. They may use adjectives to describe the sky and this is fine. In fact, it is good because the goal at the end of the lesson is not only for them to practice using fractions, but also to have different words and ways to describe what they see.)
• Now describe clouds, either the ones you see in the sky or clouds you have noticed in the past.
(If the sky is clear, then have a general discussion about clouds. Ask them to describe clouds in general. Are they fluffy, gray, low, high, etc.?)

Development

Students should get in groups of three or four and use the Pie in the Sky student esheet to go to Clouds at the BrainPop site.

They should watch the movie, look at the Learn More About Cloud Symbols section, and then play the quiz. The Learn More About Cloud Symbols section shows pie diagrams and cloud coverage, so it is a good introduction to the next part of the lesson.

Note: BrainPop is a subscription site. You can sign up for a free trial, but if you want to make full use of the site, you will have to subscribe. The site does offer subscriptions for schools, classrooms, etc.

• What are clouds made of?
(Water and dust, sometimes ice. Students should have no problem answering this question.)
• What are the different types of clouds?
(This is not directly relevant to the point of the lesson. Students should at least demonstrate, however, that they know there are different types of clouds that cover the sky differently. For instance, clouds made of water droplets are thick and can be gray, whereas wispy clouds are made of ice crystals. It's great if students remember the names and descriptions of clouds.)
• What are the different types of cloud cover?
(They are: clear, scattered clouds, partly cloudy, mostly cloudy, and overcast.)

Now give students their Cloud Cover Weather Symbols student sheets and use your Cloud Cover Weather Symbols teacher sheet as a reference to continue the questions. This activity asks students to differentiate between different types of sky, from clear to overcast.

Once students have finished the Cloud Cover Weather Symbols activity, they should then be ready to do The Pie in the Sky activity on the Plane Math website. In this activity, students learn the four types of cloud cover, their fractional component, and then assign the correct type of cloud cover to given samples of sky. The four different types of cloud cover are described as:

1. Clear – 0-1/10th covered
2. Scattered – 1/10th-5/10th covered
3. Broken – 5/10th-9/10th covered
4. Overcast – fully covered

To do this activity, students should use their student esheet again and start by clicking on the Lesson box and then follow the "Go on" button, found in the bottom right corner of each page. Once students have finished this activity, lead them in the following discussion:

• What are the four types of cloud cover described in this lesson?
(Clear, scattered, broken, and overcast.)
• How are fractions used to describe the amount of cloud cover?
(If a sky is clear, then it is 0-1/10th covered with clouds; if it is scattered, then it is 1/10th-5/10th covered; if it is broken, then it is 5/10th-9/10th covered; if it is overcast, then it is 9/10th-10/10th covered.)
• What is the method you can use to decide whether a sky is 1/10th covered with clouds or 7/10th covered with clouds?
(Students should say that they would need to put in practice what they just did in the lesson. They would need to break the sky up like a grid and count how many of the squares are covered with clouds as compared to the total number of squares.)

Note: One thing that you will want to mention to your students is that the BrainPop movie described cloud coverage differently than the activity on the Plane Math site. Tell them that neither is wrong, just different.

Assessment

The next activity basically asks students to do completely on their own what they have first done with you, and secondly in the lesson, Pie in the Sky. They will take a piece of graph paper and make a grid with as many sections as they like, then they will color in the segments that represent cloud coverage. The result is that each student creates his or her own fraction to describe the sky.

1. Hand out graph paper, and tell students to make a grid with as many sections as they like. (They may want to do something different from four or ten as they have already experienced and they should be encouraged to do so, particularly to emphasize that fractions can have any number on top or on bottom.)
2. They should color as many blocks that represent what the sky looks like.
3. At the bottom of the paper, they should put the fraction that expresses the cloud coverage.

Now, on a new piece of poster paper, repeat the opening motivation question:

• How would you describe the sky?
(Students should have fractions for answers and they may vary since students may have used different numbers of blocks to fill in, and clouds are not always easy to exactly measure. Write the fractions. They should also have answers such as clear, scattered, broken, or overcast. Students may also describe the clouds in terms of the type of clouds—i.e., cumulous, cirrus, stratus.)
• What is the difference in how you described the sky before and how you describe it now?
(Students will realize that they have new ways to describe the sky.)

Show students their first answers to the question, "How would you describe the sky?"
(Depending on your classroom, you may want to use masking tape to tape up both pieces of poster paper on the blackboard—the one you've just done, and the one from the Motivation. In any case, the point is that students be able to view their new answers as compared to the old.)

• What tools can you use now to describe the sky?
(Students may say fractions, but the point that you want to make is that they have used a combination of science and math.)

Extensions

There are several related Science NetLinks lessons. The following lessons address math benchmarks: