Erosion and Deposition

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Objective

SWBAT identify places where soil is eroded and deposited within their stream table model.

Big Idea

Soil that is eroded gets deposited in another location within a stream system. Erosion and deposition affect stream flow.

Warm Up

10 minutes

I begin the lesson by reviewing vocabulary that was taught in a previous lesson. In today's lesson, the students will be modeling erosion and deposition caused when a stream of water changes the land. In order to ensure that students can accurately identify spots where erosion and deposition occur, students must understand the definitions for these two words. 

To remind students of the meaning of the terms erosion and deposition, I provide each student group with two sentences strips. I ask the students to collaborate and come up with a definition for each word and to record their definition on a sentence strip. I then display the definitions in a pocket chart at the front of the class and review the students' definitions with the whole class.

Student-Conducted Lab

40 minutes

To help students experience success working through the lab, I display the erosion and deposition lab worksheet on the document camera. I guide students to make a prediction (in the hypothesis section) about what will happen to the land when it is met by a stream of water. I then assign student jobs for the day's lab and review the lab procedures.

The procedures in this lab differ from previous labs in three important ways. First, the students will use marine sand to help them identify areas in where the water is moving slowly and quickly. I demonstrate for students how they will add the marine sand to their stream (at the top of the stream directly under the cup, when most water is poured). I also review how marine sand differs from the sand in their stream table (weight, particle size, color). Second, the students will use toothpick flags to mark areas of interest in their stream table. A picture of a stream table with student placed flags can be found here. Third, the students will not bulldoze their soil at the end of the lesson. This prepares them to engage in the next lesson on bird's eye view drawings.

After releasing the students to independent work, I walk around and check in with each student group. I ask questions about what is happening in their stream tables and try to guide them to observe the changes in the land caused by the stream of water. 

A completed student lab sheet can be found here and a video of a student group conducting this lab can be found here.

Closing

10 minutes

To conclude the lesson, I ask students to engage in a 'gallery walk'. This strategy is used to allow all students to see the work of their peers and to compare their results with the results of others. The students are able to see different stream types and landforms in their peers' stream models.