Preventing Erosion on Our School Grounds
Lesson 6 of 13
Objective: SWBAT recognize the impact of erosion on a small portion of the school playground and design and build a system to limit that erosion.
Although this is a single lesson, it is designed to be done over a series of 5 days. It is currently divided into 5 parts, but these could be combined depending on the amount of time in a science block.
Introduction (Day 1)
I have been talking to students about how what they do can make a difference to their environment. They have learned about what an environment is and how humans influence the health of the environment though things like pollution and recycling.
Today I want students to notice things in their surroundings that show how wind and water play a role in our environment as well. I start this lesson by having students join me on the rug in the classroom. I say, "what do you know about how wind and water influence the world we live in?" We create a T-Q-L chart for what we T - think we know, Q - question or what we would like to know and L- learn(to fill in later what we have learned).
After filling in the chart, I ask students, "do you think wind or water play a role in what our school grounds look like?" I tell them that we are going to go outside and look for places where wind or water may have changed the way things look. I tell them, "we are going to bring a video camera and take pictures of anything we think has changed and then we will come back in and look at what we have found. We will take turns with the camera."
We walk around the building and students point out things like fallen branches, a pile of woodchips on a walkway that have washed to the bottom of the path, a small hill where there is only dirt and the dirt has washed over the tarred pathway below it. We film each one for future reference.
Choosing A Project (Day 2)
When we return to the classroom and upload the video (this can be done during the next science class), I say to students, "Please look at what has happened in each setting. Are these the result of wind or water?" We create a chart of the issues we found and the causes of each issue.
Next I say, "wind and water are powerful forces that can move things, as we have seen just on our playground. Do you think it matters that the water moves the wood chips or the dirt on the playground? Why or why not?" We discuss why the dirt being pushed off the garden, or the woodchips being pushed off the path would matter. (If the dirt is removed then plants would not be able to grow in that spot on the hill and the woodchips provide a cover for the ground that makes it possible for insects and worms to create habitats, and for the ground to stay moist when there is not as much rain.)
I say, "do you remember when we talked about the term erosion? When wind or water change the way things look, and carry dirt away, it is called erosion." I write the term on the board and make sure students understand this new word.
Next I ask, "Do you think we could stop the wind or water from changing these things?" (Students are always enthusiastic and eager to say yes.)
I tell students that we are going to pick a project, this time one of the water issues and see if we can make a difference in how the water is changing the hill or the path to help to protect the environment. We look at our chart and pick the area that we think we might be able to influence by voting on one of the water issue locations. (Both of the sites have to do with the effects of erosion as a result of water.)
The students decide on a location (in this case, the hill but any location that shows erosion as a result of water can be chosen).
Day 3 - Designing the System
I tell students, "today we will try to create some models for slowing the effects of erosion on the hill outside where the dirt is being washed over the walkway.You will work in small groups to design a system, think of materials you might use, the strength and shape of those materials, and create a model and then we will test the models and think about the materials and the strengths and weaknesses of each model." (2-ESS 2 -1, 2 -PS1-2).
We discuss the responsibilities for working in small groups (ie listening to one another, accepting each other’s ideas, helping each other, sharing the work and making sure everyone has a chance to be involved in the project). Next I divide the students into groups of 4 students.
I show each group a large disposable aluminum cookie sheet. I tell them this will represent the hill. They will build their design on the cookie sheet and set it up on 2 dictionaries at one end to create the hill. I demonstrate how to create the hill. I show students that I have sand and dirt that I will come and put on their tray hills when they are ready to test their creations. I will also use a watering can with a multiple holed end (like a shower head) to simulate the rain or water on their hill.
"Do you remember when we watched how the water changed the sides of our mountains in the last lesson? Now we want to think of a way to slow that water from changing a real hillside. You are making a model to try out the strength and shape of the materials while slowing the effect of water on the hillside."
I ask students to work together first to sketch their ideas and label them. I demonstrate sketching how I might try to stop the ocean at the beach from knocking down my sand castle by building a rock wall in front of my castle. I label my castle, sand and rocks.
I give students time to get in their groups, think about the problem and create a sketch of their design. I circulate around the room to observe group work and to ask questions such as why might you do that, or how do you think that will work, or what do you think would happen if...
I set out a variety of recycle materials for students to work with. I tell them that they will build their models from their designs. They can modify their design if they find something that might not work. At the end of the building time (about 25 minutes) we test and analyze the designs.
I let students work and again circulate around asking students to explain their models to me as they work.
At the end of the building time I give each group the sand/dirt/pebble mixture ( I dug up a bucketful of dirt from the playground for this) to spread on their hillsides. Next I have the students gather around each hillside in turn. I place a pan below the hill and then water the hillside (make it rain). We watch how the system students have built helps slow the erosion of the dirt. See Testing One Model.
After we have watched each design, we gather on the rug to discuss the models. We make a list of things that worked well. (2-ESS2 -1). We also talk about which materials might be the best for helping to slow erosion outside (2-PS1-2) (ie building a paper wall outside would not be durable, but a wooden wall would be). We think about what students used in their models, and what real materials we might turn those in to so if a group used clay and paper to make flowers in the dirt, we would use real flowers or bushes. If they built a fence using paper, we might want a wooden fence. If they put in popsicle stick posts, we might use wood or metal posts. I have students brainstorm real materials that might be good outside and why these might work. We talk about why certain materials might work and others might not (ie cardboard would get soggy but wood can be used outside). Metal might rust, etc.
Finally, as a class we make a sketch of what we are going to do outside to slow the erosion of dirt on the hillside. We choose the best materials for an outdoor space. I use available resources, such as parent donations, or Parent Group funds to gather the materials (wood, plants, etc.) that we will need and we invite parents to join us for an afternoon of outdoor work.
Today I gather students and parent volunteers outside with materials, rakes, shovels, etc. We all look at the hillside and the plan we have created. We decide on who will do what task, and where each part of our erosion free hillside will be built. I try to assign one adult and 3 - 4 students to each task (I have divided up the tasks ahead of time to make this easier to manage).
I am available to help in any area, and to provide oversight as necessary. At the end of our work, we clean up and photograph the hillside. After the next rainstorm we come outside to see if our plan has helped to eliminate erosion of the topsoil.
We all celebrate our finished project by creating a video of the whole process.
Students have identified a real-life problem caused by water, designed a model to correct the problem, analyzed which model, or model parts were the best, discussed materials that could be used to build the actual system, and finally built the system and seen how it worked.