Students will separate soil components: sand, silt, and clay, into three separate sample groups. Next, they will learn how to determine the relative composition of different soil types.

Prior to the lesson soils should be collected in one pound coffee cans from a variety of areas such as the school yard, home yard, local park, or forest. Label each can accordingly. (Students may also list plant life found in each area from which a soil sample is taken)

Distribute the "Soils Composition Worksheet" to the class.

Students may work in pairs or in small groups. Each group should be provided with two quart jars with lids, a beaker, a wide pan such as a cake pan, and a container of water. Fill both jars one-quater full of soil from the same site and add water until both jars are two-thirds full. Place the lid on one of the jars, shake it vigorously, then set it aside to allow soil particles to settle. Once this is done, add a small amount of dish detergent to the other sample. Place the lid on this jar and shake it vigorously for about two minutes (detergent breaks the surface tension and allows soil particles to easily separate).

Instruct students to check the "Soil Comparison Worksheet" for questions that relate to each of the following experiments. Answers to the questions should be recorded on a separate sheet of paper.

For the detergent jar:

Pour everything that does not immediately settle out in the detergent jar into the beaker. Add a little more water to the jar and shake again. Pour this water into the beaker as well. Sand will remain in the jar. Dry (through natural evaporation or the use of a hot plate), measure, and record the volume of sand in the jar to the nearest one-quater teaspoon.

Allow the particles in the beaker to settle for 30 minutes. Pour the remaining cloudy water into the pan.

Dry, measure, and record the volume of silt that settled out in the beaker, to the nearest one-quater teaspoon.

Let the remaining water in the pan evaporate. Clay particles will remain in the pan. Measure and record the volume of clay in the pan to the nearest one-quater teaspoon.

Once students obtain data from this experiment, have them add the numerical volumes of sand, silt, and clay together. When this is done, have them calculate the percent of the volume of sand, of silt, and of clay in each sample.

Distribute the "Classification of Soils Chart". Have the students classify the type of soil tested using the directions on the chart.

Have students report their findings to the class.

For the soil and water jar:

View the soil sample in this jar that has been allowed to settle and form soil layers.

Lead the students in a discussion about this jar's contents by asking:

1. Why did the soil particles settle in layers? (The size and weight of the particles determines if they will settle in the top, middle, or bottom)

2. Which layer is sand? silt? clay? (sand is made up of the largest particles and will settle on the bottom; silt is made up of medium sized particles and will settle in the middle; clay is made up of the smallest particles and will settle on the top)

3. How do particle sizes influence soils (soils percolation rates are dependent on soil particle size, and a soil's ability to hold moisture are influenced by particle size as well)

4. Pinelands soils are usually sand, or a combination of clay and sand called "loam". What are some of the possible combinations that are found in the "Composition of Soils" chart? (sand, loamy sand, sandy loam, sandy clay loam, and sandy clay)

5. Is there such a thing as a "best kind of soil" for gardening? (While there is no "best soil" for gardening, water moves rapidly through sandy soils and they retain very little moisture or minerals. Water moves more slowly through clay soils and they readily retain moisture and minerals. Different plants have adapted to different soil types-for example cranberries and blueberries thrive in the acidic, sandy, nutrient poor soils of the Pinelands, but they would not do well in nutrient rich clay soils.)

The teacher is cautioned to save some clay and silt samples as they will be required for lesson 3!

EVALUATION:

Students may demonstrate in class discussion and/or by completion of the "Soils Composition Worksheet" an understanding of the concept that Pinelands soils are composed primarily of sand with some clay occasionally present.

FOLLOW-UP:

1. Create "new" soil types by mixing different percentages of the sand, silt, and clay samples separated in the water jar experiments. Refer to the "Composition of Soils" chart to determine percentages typical of different soil types (like "silty clay"). Plant seeds like beans or radishes in the "new" soil and observe and record the development of these seeds. Make sure that the seeds are kept in the same conditions and given the same amounts of water. Based on seed development, draw conclusions about which of the "new" soil types is most supportive of plant life.

2. Place sand in one container, silt in another, and clay in a third. Plant a bare root plant into each soil type. Add the same amount of water to each container, water each plant just once. Observe and record how long it takes for each plant to wilt. What does this illustrate concerning different soil's ability to retain moisture?

This lesson will introduce the students to the following vocabulary words:(click on the word to see its definition-use your browser's back button to return to this page)

clay, composition, loam, silt

Science standards:

5.1-All students will learn to identify systems of interacting components and understand how their interactions combine to produce the overall behavior of the system.

5.2-All students will develop problem solving, decision making, and inquiry skills, reflected by formulating useable questions and hypotheses, planning experiments, conducting systematic observations, interpreting and analyzing data, drawing conclusions, and communicating results.

5.5-All students will integrate mathematics as a tool for problem-solving in science and as a means of expressing and/or modeling scientific theories.

Evaluate our site! Click on the Grade Page icon to go to our evaluation page. Won't you please take a minute to tell us how we can better help you bring the Pinelands into your classroom