In today's lab, students will run water through their stream table after creating a slope. I begin the lesson by asking students to predict whether slope will affect erosion in the stream table model. A video of my students discussing their predictions can be found here. I begin the lesson with student predictions because this connects to students prior knowledge and asks the students to begin to think about the relationship between flow and erosion.
After students share their predictions, I review with students the terms controlled and manipulated variables. Understanding these terms is very important to students as they are included in our state's summative science assessment. I review the controlled and manipulated variables in lab work throughout the year to build student understanding. I ask students to name the things which are kept the same (controlled) in the lab and to name the one variable that is changed (manipulated). I record these variables on the white board before the students begin the day's lab work.
In today's lesson my goal is to have students understand the relationship between slope and erosion. I accomplish this by providing students with an opportunity to compare and contrast their results with those of a previous lab. I distribute the slope lab recording sheet to all students and review the procedures for the day's lab work. I then provide students with the time to conduct the lab. Students record their results on the rushing rivers lab worksheet by drawing a bird's eye view drawing of their stream table model and measuring the stream width and length and the width of the soil deposit. A photo of a student stream table model can be found here.
After the lab, I ask students to record a formal conclusion for this experiment on the lab sheet. On my state's summative science assessment, student conclusions are evaluated on a four point rubric. To earn full credit on a conclusion, the students must write a concluding sentence (which addresses the purpose of the experiment), write the high and low data points, and use comparative language. I introduce conclusion writing in this lab because the students have data from two previous labs that they can use to support their conclusion. A completed conclusion that earned a score of 4 can be found here.