This is a fun experiment I do with my students after they have learned about negative feedback systems. I challenge them to test a way to bring their bodies back to "normal" after exercise. They get the option of testing blood pressure, temperature or heart rate. The directions instruct students to use Vernier probeware. If you don't have these available, you could change the directions to just using heart rate and have them take their own pulse. They are required to generate their own data table and analyze their own results. I love this activity at the beginning of the year because things don't always go "as planned" for students while they are testing their variable they chose and I can see how they perform under pressure and to what extent they have developed a growth mindset.