We begin class with a quick review of the manner in which reaction rates can be adjusted and controlled because the students are going to spend the rest of the class period conducting an experiment in an attempt to control reaction rates. The students share their ideas for controlling reaction rates with the class. I review the reaction rate lab and proper safety guidelines with the students prior to them entering the lab.
The students work with their group members to finalize a hypothesis and writing a materials and procedures list for the first trial of their experiment. The students must have these items approved prior to obtaining the necessary materials to conduct their experiment. After completing their first trial, the students are asked to reformulate their hypothesis and rework their materials and procedures list as necessary based upon the information gained from their first trial. While in the lab, the students conduct three trials of their experiment with the goal of getting as close as possible to their target time.
During this time I circulate through the room asking students to explain their hypotheses and their results. In this video, I ask the students about Collision Theory. The experiment conducted by the students addresses NGSS SP3, SP4, SP5, and SP6 as the students design and conduct their own experiments and then use their data to create a chart and graph. The students also analyze their data to draw conclusions about controlling reaction rates. In this student work sample, the students could have provided a more detailed explanation of their determination regarding their hypothesis by providing quantitative data.
At the end of the lab, I lead a group discussion by asking the students to share their results with the class. I ask the groups to also share the process by which they completed the three trials and the thinking that led to their decisions on how to conduct the trials. I am careful to question and probe until the students provide evidence for their trials. This portion of the lesson addresses NGSS Cross Cutting Concept of Cause and Effect as students are required to analyze their data and look for patterns to identify cause and effect relationships. I also ask the students to respond to their classmates by asking questions about how experiments were conducted.