Earth Science Week Classroom Activities

How Much Soil Is There?

Activity Source:

Adapted with permission by the Soil Science Society of America from Oklahoma Ag in the Classroom.

Background

All living things depend on soil to live. What are some of our important natural resources? Your answers might include materials such as oil, water,
coal, trees, animals, and gold. All of those areimportant natural resources, but we often forget to mention one of our most important natural
resources: soil.

Materials

• Apple(s)
• One sharp knife (for teacher demonstration) or plastic knives (for student participation)
• Cutting board
• Paper towels
• A computer with Internet access

Procedure

1. Print copies of pie chart graphs from <http://www.soils.org/files/about- soils/earth-science-week-2007.pdf> and share among students. Cut the unpeeled apple as the teacher explains the fractions shown.

2. Pretend that this apple is planet Earth. Notice how its skin hugs and protects the surface. Cut the apple in quarters. Three of the four quarters
represent how much of the earth is covered with water — oceans, lakes, rivers, and streams. Set three of four quarters aside. Discuss: Do you
know what percentage that is?

3. Left is just one quarter (25 percent), representing the portion of our earth that is dry land. Take this quarter and cut it in half. One of these halves represents land that is desert, swamps, polar, or mountainous regions where it is too hot, too cold, or too high for humans to be productive. Set this half aside.

4. The other half (one-eighth or 12.5 percent of the apple) represents where humans can live and grow crops. Slice this section lengthwise into
four equal parts. Now you have four 1/32nds (3 percent each) of an apple.

The first of these represents land too wet for food production. It isn’t swamp land, but it may flood during the growing season. The second section
represents land that is too rocky and poor to grow food. A third 1/32nd represents areas that are too hot. Set these three sections aside.

5. The last section (1/32nd or 3 percent of the apple) represents the area of the world developed by humans. Now, carefully peel the last 1/32nd section. This small bit of peel represents the portion of our planet that is soil on which humans depend for food production and similar uses. So, like water and air, soil is a very important and limited natural resource.

Follow-up activities:

Have older students rank resources in order of importance. Are some resources equally important for life? Are others important because we rely on
them in our modern world? Have students identify (or show younger students) areas on a map or globe where crops cannot grow.