Controlling Erosion

In this lesson, students apply what they know about weathering and erosion to engineer a solution that prevents rainwater from washing away a sandy hillside. 

• Engineers are people who use scientific knowledge and mathematics to solve a problem by creating new technologies, and that similar to scientists, engineers follow a process to guide them as they develop a prototype that solves the problem.
• There are many solutions that engineers can come up with to reduce the amount of erosion that takes place.
  
  

• How are engineers different from scientists?
• What is an example of a problem that an engineer might try to solve?
• What is a technology that solves a problem?
• Why do engineers follow a process, similar to how scientists follow a process?
• Where does erosion happen?
• Why might erosion be a problem for some people?  
• What can engineers do to slow down erosion on a hillside?

Misconception: Erosion always happens quickly.

Fact: Erosion can occur quickly, but it often happens very slowly, over hundreds, thousands, or millions of years.

Misconception: Erosion is always “bad.”

Fact: Erosion isn’t “bad” or “good.” Many landforms are created by the deposition of eroded Earth materials.

Misconception: Earth’s surface, including its rocks, doesn’t change.

Fact: Earth’s surface is constantly changing. Some of these changes happen quickly, and other changes happen very slowly.

Change: to make something different from what it is know

Engineer: anyone who uses scientific knowledge and mathematics to solve a problem by creating new technologies

Erosion: the movement of small pieces of rock, soil, and sand from one place to another by wind or water

Prototype: a smaller version of what will be engineered

Weathering:  the breakdown of Earth materials (such as rocks, sand, and soil) into smaller pieces; can be caused by wind, water, or living things

The Day the Falls Stopped 

Years ago, a group of engineers did something no one else had ever done. They stopped the water from going over one of the waterfalls in Niagara Falls.

Engineers are people who use scientific knowledge and mathematics to solve a problem by creating new technologies. A technology is anything that people have made to meet their needs and wants.

All engineers start with a problem. This makes engineers different from scientists. Scientists always begin with a question.

Engineers in Niagara Falls had a problem. The water was eroding the land too quickly. Erosion isn’t always bad. But it can sometimes cause problems for people. This can happen when people use the land that is being eroded.

When engineers define a problem, they include the criteria. The criteria are the needs the solution must meet. In Niagara Falls, there were two criteria. One was that the erosion of the land had to slow down. The other was that the water had to keep moving over the land.

Engineers also include the constraints. Constraints are ways the solution is limited. Cost is a common constraint. Engineers have to think about how much their solution costs. Materials are another constraint. Engineers can only use the materials they have.

For the hands-on activity of this lesson, students act as engineers by designing a solution to a problem. First, students summarize the problem presented in the engineering scenario, which is that a sandy hillside at a school gets washed away in heavy and light rains. Students then identify the correct solution criteria and constraints. Students draw a scientific diagram of their chosen prototype solution and use their diagram as a guide for creating their erosion-slowing prototype. Once students build their erosion-slowing prototype solution, they test their prototype to determine how well it solved the problem, meeting the criteria within the constraints. They collect and analyze observational data on the amount of sand that was washed away from the hillside for each of their prototype solutions, looking for evidence in their observations about which prototype best solved the problem. Students use the data they gather from their first prototype solution to improve their second prototype so that it better solves the problem. Finally, students evaluate both prototypes to explain how well their prototype solved the problem and present their analysis to the class.