I began my search for a 21st century topic by looking through our text from the last class Teaching Science in Elementary & Middle School by Buxton and Provenzo (2007). I was intrigued by Experiment #86 titled "Modeling Nuclear Half-Life". There is a lot of discussion in the news about radioactive materials, especially in a way of eliminating bacteria in some fresh food. I knew nothing about the topic, but found the topic intriguing. The activity involves food, which my seventh grade students would like and I thought it might tie in with a chemistry unit I teach.
First, I needed to understand what nuclear deacy and radioactive half-life mean. It deals iwth the time it takes for one-half the amount of a radioactive element to decay. It does not decay in a biological sense, but the element transforms itself into a different, more stable element. One of the websites that I found useful in helping me understand the concept was http://www.discoveryeducation.com/teachers/free-lesson-plans/elements-and-compounds.cfm. This site had the same basic activity as the one in the book. This, however, also had definitions for what the model in the activity are meant to represent. It also had extensions that tied to everyday compounds and the work of Marie Curie. Links at this site included a link to an iteractive tourof the fundamentals of matter and force http://particleadventure.org/index.html. I could see using this link for further information about the atom.
The activity to be done is to use 60 M&Ms to represent atoms of a radioactive element like polonium. After one minute, half of the atoms will decay and be transformed into a more stable element: in this case, polonium is transformed into lead. Students create a table showing how many M&Ms are left after one, two, three, five, and ten minutes. The web site that best described what was happening came from videos for middle school at http://www.globalshiksha.com/content/radioactive-decay-for-middle-school. I would use this resource after students do the activity. The video gives an in-depth explanation of parent and daughter elements. It shows a version of the activity already done and how it applies to nuclear decay. The video is also engaging because it gives history and explanation that is language understandable for middle school students. In addtion, it shows how scientists apply radioactive decay to carbon dating.
A final source came from http://phet.colorado.edu/en/simulation/alpha-decay. This showed a simulation of how elements change from radiactive to non-radioactive elements. It also projected a timeline that showed how the halflife is not the same for all atoms in a given sample. Again, this site gave another link that described the application to carbon dating http://phet.colorado.edu/en/simulation/radioactive-dating-game.
All of these tools will help prepare students to be scientifically literate for several reasons. First, it offers a model that students can manipulate and graph. The graph has very predictable behaviors that students can apply to any radioactive material. The resources do not teach the concept in isolation, but show history and application to other relevant scientific concepts. A challenge may be that this is such an abstract topic, students may have difficulty seeing how it is relevant to them. For me, it would also be a challenge to have enough computer time for students to explore the interactive sites. I hope that the activity and, history, and video would provide enough information for students to get a basic understanding.
