Why do some things get colder (or hotter) when they react?
This high school physical sciences unit on chemical energy starts out with students exploring a phenomenon where mixing two room temperature substances together results in a dramatic drop in temperature. This leads to disagreements as to what is happening that causes thermal energy to "disappear"—what is that energy being used to do? This question motivates a series of investigations examining salt dissolution and using magnets as a model for both inter-molecular and intra-molecular bonds. (PS1, PS3)
Why Don't Antibiotics Work Like They Used To?
This high school unit on natural selection and evolution starts out with students exploring the case of a young girl with a life-threatening infection of pan-resistant bacteria. This case sparks questions that lead them to investigate the growing prevalence of such cases and the discrepancies between antibiotic use in their communities and CDC recommendations. As they develop a model to explain how bacteria populations change over time, they expand their investigations to look at whether similar population changes are occurring in a population of birds (Juncos). (LS4)