STEM Lab: Day 1 - Soil Drainage and Retention
Lesson 7 of 8
Objective: SWBAT test drainage and retention of different soils and determine how each one differs.
My class has been doing STEM labs all year. Our typical cycle is one week per month when we actually leave our classroom and I team teach with another teacher in another classroom. This time due to crazy scheduling it didn't quite work out that way and so I am doing the whole experience in 2 days! Whew! I always follow the engineering design cycle for STEM lessons which keeps us focused and makes the learning really purposeful. For this first lesson, we are going to complete the first 3 steps - 'Think, Plan, and Test'. The reason I feel I can get all of this into one class period is because my students already have background knowledge about soil - we have already completed several lessons about the properties of soil, so I am using the 'Think' section almost like a review. Then, the 'Plan' section is really teacher supported because of the way this experiment is set up. I already have the materials ready and the students are not inventing how to test the samples -- the lab is actually testing them. That is a little different than our other STEM labs have been, so I think I can do that much faster that usual! Then, my students will test the samples, which will be set up and they basically scoop the sample into the cup funnels and add water with droppers and count, to see how much water it takes before it drips out of the bottom again. Then, they record their data. They will test 4 samples, so it should not take too long!
This lesson aligns to Essential Standard 1.E.2.1, Summarize the physical properties of Earth materials including soil and water that make them useful in different ways. Listen to my Explanation of Essential Standards and Essential Question.
If you need more information before teaching this lesson, check out this page.
*Bottle funnels - Decide if each student is going to do this experiment themselves (totally feasible with a smaller class size) or in pairs. This lesson needs to be hands-on and not a teacher demonstration - the students need to really see what is happening! Based on what you decide, you need that many funnels!
*1 sample each of clay, silt, and sand, and any other soil samples (potting soil would be interesting!) per group
*2 plastic spoons per group
*1 plastic grocery bag per group
*1 eye dropper per group
*1 stopwatch per group
*1 Stem Lab - Soil Drainage and Retention Recording Data Sheet per student
To start this lesson, I have my partners that will conduct this experiment together selected already. Sometimes I let the students choose, but because we are on a short timeline with these lessons I need them to work quickly and collaboratively, so I chose this time! So, I already had a list posted on the board. I say to my students,
"Please bring your science journal and your pencil and sit with your partner on the carpet".
As they come to the carpet, my intern sets up the experiment materials on the table which is a super time saver! Otherwise, I would have two students help do that while I continued with the lesson.
I use this PowerPoint to introduce the vocabulary words 'drain' and 'retain' to my students so they understand that drainage is the process of the water moving through the soil samples, and retention is the process of the water staying in the soil samples. Then, the pictures in the PowerPoint and the questions guide me through a conversation with my students about how the types of soil can change how weather reacts with the soil, causing flooding that can devastate areas.
But, there can be a happy ending! Scientists work with farmers to prevent erosion by changing soil types and planting different crops to minimize the impact of flooding when they can. This conversation works to define a problem (flooding and erosion) with my students that leads to the development of a new tool or solution (working with farmers to plant specific types of soil and crops), which supports Science and Engineering Practice 1.
In their journals, I ask students to write the definitions for 'retain' and 'drain' on their lab recording sheets and then we move on to section 2, 'plan'.
For this part of the engineering design cycle, I typically have students develop their own ideas for how to create something or how to solve a problem. However, since this is an experiment and not a problem solving lab, I give specific directions on how to put the entire amount of soil into the bottle funnel and I explain how to complete the recording sheet. I show the sheet on the projector and go through it so the students know how to record their data. As we go, I say,
"Now that you understand what you will be doing today, how will you know how much water each sample retains before it drips out of the bottom?"
I want students to verbalize that they are going to actually count the number of drops they put into the soil sample, and that they are going to wait a few seconds between the drops. Also, they are going to time it - for that, they need a partner, because one person cannot remember to do both things! This ties in Science and Engineering Practice 5, 'Using Mathematics and Computational Thinking' and 21st Century Skills - collaboration. Practice 5 requires that students decide when to use qualitative or quantitative data, so, as part of this conversation they need to know that they are recording the number of drops and the amount of time it took for the sample to drain. Some students may not have used a stopwatch before so they may need a quick tutorial on starting, stopping, clearing, and recording that data before beginning the experiment.
Planning and conducting an investigation supports Science and Engineering Practice 3. In this investigation, students are producing data to serve as the basis for evidence to support the need for farmers and scientists to use different types of soil to prevent erosion during flooding. This directly supports this Practice, and could also be furthered to include other natural disasters where soil saturation cause devastation, such as famine.
As part of the planning stage, I also ask,
"Let's make a prediction as well. Who can explain what a prediction is? That's right - a guess based on your knowledge of a topic. What do you predict will happen when you drip water through the sand?"
Since we live near the beach, I assume that my students will know that it will drain quickly. I record some of their predictions on my board to return to in tomorrow's lesson. Then I ask the same question about silt, clay, and potting soil. Making predictions based on prior experiences also supports Practice 3. Then I say,
"Now, your samples are clearly labeled. Before anyone begins to use the droppers and count their water drops, I should see you writing in your journals what each soil sample is. Good scientists take clear notes so that they can remember what they did and so that they can share their information."
As students transition into the "Test" stage, I help them to get started to make sure they understand the lab and then I check for accuracy as they work.
For the students to test their samples, I took single serving water bottles, cut them in half and tied a piece of material over the opening with a rubber band. I inverted the original top half, taped it into the bottom half, and voila! a soil drainage tester. Now, for students to use these multiple times, as they will in this lesson, they will have to clean out the top part - that is what the grocery bag is for. So, the students put soil sample one into the bottle tester, use the dropper to test while running their stopwatch. As soon as the water drips through, they stop the stopwatch and record how many water drops it took and how long it took.
Then, after they have tested sample 1, they will dump their first soil sample into the plastic bag and use a paper towel to wipe out the bottle as much as they can. They can use the spoons to scoop soil sample 2 into the bottle, and start again! Alternately, you could have 4 bottles made per group.
As the students work testing their samples, I walk around and spend time with each group, checking for accuracy and understanding. It is important that the students understand what they are doing - measuring how well the water drains through the soil - in order to compare the four samples.
At the end of the 'Test' stage, I ask my students to put all of their soil samples in their grocery bags with all of their other materials and bring their journals and pencils to the carpet.
This lesson will be continued tomorrow as students analyze their data and communicate the results, but for today I finish the lesson by asking,
"What did you find out?"
As students share, I listen for any misconceptions that I need to clarify or patterns that emerge that I want to bring back up tomorrow during our conversation.
Communicating results and sharing information supports Practice 4.