Soil Secrets-Different Dirts
Lesson 3 of 8
Objective: Students will be able to build a model to observe the different layers of soil.
I ring my chime to get the class’s attention. I announce that we were about to begin the third Science lesson in our unit about soil. I ask them to return to the carpet squares and ‘Show Five’. I aim to always start lessons with a way- however simple- to connect the material with a real life application.
Once seated, I ask for three volunteers. When they come up, I say, “What do you notice about your classmates?” “They’re all kids.” “Two are girls.” “So you noticed that they are the same and different. And they do the same and different things. Let’s look at our soil and discover what they have in common..and how they’re different.”
Whole Group Instruction
I revisit the book, Dirt. As I read the next several pages, I stop to introduce some important new vocabulary terms. “There are many different types of soil. Each type has it’s own unique purposes and qualities. The heaviest layer is rocks. Because it’s heavy, it’s at the..”. “End?” “No. Can you think of another way to say it?” “Bottom?” “Right!” As I ask these questions, I use my hands as visual aids, to illustrate my anticipated answers. Techniques like this help English Learners better access the material by scaffolding the concepts.
“There are different kinds of soil that are at different places in the ground.
1. The bottom layer made up of rocks and pebbles because it’s the heaviest.
2. The next layer up is sand.
3. Above that comes silt.
4. Before that is clay.
5. At the top is humus." .
I show them a picture from the book that perfectly illustrates these layers. As each new vocabulary word is introduced, I have the students repeat, “Rocks”.. “Pebbles”.. “Sand”.. “Clay”.. “Humus”. This teaching strategy is another helpful way to help English Learners to access the material. “Layers of rocks and pebbles are good for drainage because there’s a lot of space between them. This makes sure that water gets everywhere. Why would that be important?” “So plants can grow better?” “Perfect! Sand has grains that don’t fit together either, but they’re smaller. Water runs over sand, but when you mix it with other soil, it can make a better habitat for plants to grow. Silt is made from fine, almost powdery grains that do fit together, so it holds water but will be very heavy unless it’s mixed with organic matter. Humus is also important because it makes the mineral grains more crumbly and provides lots of nutrients for the plant and animal life in the soil. It’s all a big soil recipe.”
After the whole class instruction finished, I told them “It’s time for us to explore these layers. We’re going to mix some of the soil we collected with water. Then we get to shake it up and wait to see what happens. Any ideas?” "The soil will kind of mix?" "Anything else?" No other input other than, “Do we get to take it home?” That’s become a common question lately. I’m always happy to hear it because it means that the students want to keep a tangible reminder of their learning. "Probably, but let's see where the learning takes us." I give this answer because sometimes, the work product is better suited at school so the students can refer back to it during future learning. It depends on the moment, so keep flexible!
Small Group Instruction
• Spoons (or any kind of scoop)
• Small Jars (one for each type of soil)
• Soil (leftovers from collection)
I ring the chime and ask them to go to their tables. “What should be the first thing we do?” “Look at it.” “Right. People who study soil need to observe it and separate the types so they can figure out how to change it and make a successful place for plants to grow. There’s a few steps we need to follow to do this.”
• First, put two spoons of soil into the jars.
• Next, add water so the jar is almost filled.
• Then, shake up the jar.
• Last, set it back down on the table and watch it separate.
I remind them that patience is a part of Science process, “It may take a while for this to work.” I put a jar on each table next to the container of soil. As the students proceed, I walk around and help them as needed. When they are finished with the brief beginning of our demonstration, I say, “Let’s check on it after recess to see if we can detect any separate layers.”
After recess, I have the students go back to their carpet squares to review what we need to do when we look for soil layers. I model the process “What I would look for in the jar? Hmmm..I want to see if I can see soils that look different from each other.” I move around the classroom as the students use magnifying glasses to examine the jars for soil layers. I’m listening for comments that relate to the ways the soils look different.
Once the observation is complete, I ask the students to head back to their carpet squares to use a chart to record their observations to labels and (simple!) illustrations. “Let’s share some of the things we observed.” “I saw some wood float to the top.” “Great. The floating part was humus. Let’s record that on our chart.” “I saw big pieces near the bottom.” “That layer was... “ “Rocks” “Right, they’re at the bottom because they’re heavy and water moves through it. Let’s leave the jars on the table so we can see if anything changes. Since this lesson is an exercise in recognizing these differences, this simple formative assessment is an adequate way to measure the success of the lesson.