As the students enter the room they take out their journals and respond to the prompt: What are some items that impact pulse rate? Why? How do you know?
I circulate through the room to read their responses as the students work on the prompt. The students know that running and other exercises increase pulse rate, and many of them are able to explain in general terms why this happens. I encourage the students to think of other activities that may impact pulse rate, challenging them to go beyond the idea of exercise.
In this student journal, the student mentioned suspenseful situations, but did not explain how she knew. Other items listed by students included lying and taking medicines/drugs.
Once the students have had a chance to write down their thoughts, I ask them to share their journals within their small groups. This gives them a chance to discuss their thoughts and refine their ideas. I then ask for volunteers to share their answers with the whole class. As the students share, I ask them why the item they mentioned impacts pulse rate and how they know. This teaching step is critical. Listing ideas demands little thinking beyond calling on memory. By asking students why and how, we are guiding them to dig into their understanding.
This is the video that students are expected to view and take notes on prior to this class.
We briefly review portions of the notes together as a class. Included in the notes is how to take your resting heart rate. A simple accountability check, as well as an interesting and personal hook, is to have the students share their resting heart rate with the other members of their group. I also tell the students my resting heart rate. Sometimes this leads to a discussion of the differences in resting heart rate and what may cause the difference.
I then ask the students to take out their Chromebooks and open the Blood Pressure worksheet. While they do that, I load the Cells Alive website on the SMARTBoard. We complete the first part of the worksheet together by examining myocytes and how they function individually and as a group. At this point in the lesson, I want the students to be able to recognize that a cardiac myocyte is a specialized cell in the circulatory system, similar to my expectation that students recognize neurons as being specialized cells in the nervous system from the previous unit. Reviewing the different types of cells that make up the heart addresses NGSS MS-LS1-1 and MS-LS1-3.
After reviewing myocytes and their function, I have the students revisit the idea of pulse contained in their initial journal entry. I have them work within their small groups to complete the guiding questions from the worksheet.
They begin this process by recalling and writing the definition for pulse. From there, I have them review how exercise impacts pulse and then explain why that reaction occurs. Once they have reviewed this information, they need to develop their own experiment to explore how something impacts pulse.
While they work on this portion, I stop and discuss ideas with each group. I try to students them away from obvious experiments, such as testing to see if running will impact pulse rate. I provide them with a few examples, primarily examples dealing with the senses, since we just finished reviewing the nervous system. For instance, I ask them if they think different sounds may impact pulse rate or if different tastes could have an impact.
While the worksheet has a section for actually conducting the student created experiment, the students do not have time to complete the experiment during this class period. Some of the students choose to complete the experiment on their own time and some of them use the experiment as their circulatory system capstone project. Designing and conducting their experiments as well as analyzing their data address NGSS SP3, SP4, and SP6, respectively.
This is a student work sample for an experiment that I did not authorize completion of due to its potential negative impact on students.
At the end of class, I ask each group to create a CER, using their hypothesis as the claim and using their prior knowledge to support their claim. Sometimes students develop a hypothesis without connecting the information to what they already know about the topic. Having the students create a CER requires them to think critically about and support their hypothesis.
Once they have had time to write their CER, I ask the groups to share the experiment they designed with the rest of the class. The group shares their experimental design and then the other students are encouraged to ask questions about the experiment. If no one else asks, I ask the group to explain the reasoning behind their hypothesis. In general, the students have developed their hypothesis based upon prior experiences. Since many of the experiments the students design deal with trying to increase heart rate, I ask them to explain whether or not the experiment should be conducted and why. If the students do carry out the experiment, and some of mine chose to do so, they can then add their data to their CER.