Radioactive Decay of Candium

Last week, I posted on G+ a brief preview about an in-class learning activity that I do in my geochemistry course, which I refer to as the "Radioactive Decay of Candium".  The idea is to use a student-centered activity in class that is enjoyable & interesting in order to learn about how radioactive decay works.  I didn't originate the idea, rather I've taken the main idea from an activity on the SERC geoscience education website & modified it a bit.

The activity begins with a very short discussion about how radioactive decay works, but really I want to get them going quickly, so we talk about the fact that each m&m has a 50/50 chance of landing m-side up or m-side down, a lot like flipping a coin.  So I give them each a couple hundred pieces, a bag, and a couple of pieces of clean, white paper, and a handout.  Their job is to count the pieces, place them in the bag, shake them up, pour them out, remove those showing m-side up, and count the ones that remain.

Fig 1. Science in progress!

Those that remain are placed back in the bag & the process is repeated.  Each time, they record their results on the board.  After they reach zero m&ms, I give them a second handful of pieces, they count those & then add them to their first pile and do it all over again with a larger sample.  At this point, they might have ~300 pieces.  This time, however, those that "decay" each turn might get eaten.  After all of the groups (I usually have them do this in pairs) have finished, everyone records all of the data.  We then walk through the graphs they have to create with the numbers, now working on their own.  So here's a graph of all the trial runs, including the "class total", which is just a sum of all pieces on each step.

Fig. 2.  Decay curves of Candium for all experimental runs.  

This obviously shows the number of pieces that remain on each turn after they shake them out & separate out the "decayed atoms".  Then I have them calculate the percent of the total number of "atoms" that have remained on each turn, which looks like the figure below.

Fig. 3.  Percentage of total atoms that remain on each turn for all experimental runs.

I like the comparison of the two graphs, in that it shows that no matter how many atoms you start with, the decay in each case is the same percentage.  It's a fun activity that helps students really connect to the idea of radioactive decay, and a tasty one too!

Google+ at ScienceOnline

In my last post, I introduced the new Geoscience Community on Google+.  Here, I'd like to point folks to a recent talk by Fraser Cain about Google+ at the ScienceOnline Conference.  +Fraser Cain is an astronomy enthusiast, blogger, publisher of Universe Today, and almost any scientist who's been involved with Google+ over the past year & a half is probably familiar with his name.  If anyone has taken science on G+ into awesome mode, it's him.  He's done some really cool things with G+ and astronomy, such as hosting hangouts as Virtual Star Parties, getting people from all over to stream the views through their telescopes over the web.  He & others who've joined him have given more people the opportunity to see something amazing in the night sky live through a telescope than anyone else in the world.  Tens of thousands have viewed the Hangouts he's hosted.  He has been so successful that Google decided a while back to make a short documentary/advertisement about what the way they use the technology.  And this past year was full of fantastic events, from the transit of Venus to Curiosity landing on Mars and others.  

The video for his talk includes others as well; he begins to speak about 12 minutes in, and lasts until ~33 minutes.  If you are interested in science & social media, it is well worth taking a look at, especially if you've not used G+ before.  What he's accomplished in the past year & a half with this new technology is pretty special.  

I would love to see what could come of geosocial activity through G+.  It is still very much in the beginning stages.  There are a few geos who are using G+ regularly, but there's so much room for so many more, especially those who've not yet connected with fellow professionals.  The Geoscience Community has drawn in some new folks this past week, which is excellent, and they've made some great contributions.  One feature that geoscientists aren't using much yet are the hangouts.  We've used them some in the past, driven largely by +Ron Schott 's geology office hours, but they've not yet really caught on.  I'd love to see geos use them as effectively for Earth Science as Fraser has for Space.  Geoscience is right at the heart of many of the major problems facing the world today; capturing people's imagination shouldn't be an issue when you've got volcanoes & earthquakes & velociraptors on your team.  That could be really fun.