Lesson 14 of 18
Objective: SWBAT compare stream flow in a stream system with and without landforms which alter stream flow.
I begin this lesson by distributing a copy of the landforms lab recording sheet to each student. I inform my students that in today's lab, they will be working on making accurate predictions based on evidence from their observations in past labs. Unlike in the other labs in this unit, the students will set up their stream table before making a prediction.
Prior to science time, I ask students to collect a rock or stick from the playground area. Each group will use one to three rocks and one or two sticks to make obstacles in the path of their stream during the lab. They will also create hills (made of humus) in their stream tables.
To begin the lab, students bulldoze their soil and set up their stream table as they have done in previous labs. The students then work together to determine where to place the hills, rocks, and sticks in their stream table. An example of a group's stream table, with obstacles, can be found here.
I then ask students to create a visual representation of their prediction. To do so, the student creates a bird's eye view drawing of their stream table and uses a red pen to predict the path the stream will take when they run water through their stream table. I then ask students to share their predictions with their peers. A video of my students sharing their predictions can be found here.
After making predictions, I provide students with time to conduct their lab. In this lab, students will pour two liters of water through the stream table. As the water moves through the model, I ask students to record their observations on their lab sheets.
After the lab the student's stream tables have changed dramatically. A view of a student's stream table after the lab can be found here. I ask students to create a second bird's eye view of the stream table. This time, I ask them to use the red crayon to chart the actual path of the stream. A sample of a student's completed lab sheet can be found here.
To conclude the lab, I lead a class discussion comparing and contrasting predicted results and actual results. The students frequently remark that they were surprised at the power of water to move obstacles. In all of the stream table models, at least one obstacle was either eroded away or moved by the stream of water. Students often note that there was a greater degree of erosion (as evidence by soil deposit and runoff clarity) than in other labs. As we discuss the results, I encourage students to support their statements using evidence from the stream table.