I don't get my science geek on very much anymore. I know that sounds odd since I am a science specialist, but my role is more about pedagogy and teaching tools than actual science "stuff." So, I'm overdue to share a good science story. The one which follows is one that my 9th grade science teacher told me. Although I hate to admit that it is nearly 25 years later, it is still a tale that I shared with students of my own each year...and a colleague earlier this evening. It deserves to be passed along because it's just so goshdarned good.
I used the story in order to help students understand catalysts: enzymes that speed up chemical reactions without being used up in the process. In my own poor way, I would illustrate the story while I told it...much to the delight of my students. (I am a terrible artist and the stick cows required for this tale were really at the edge of my abilities.)
Farmer Bob has three sons: Bob, Jr.; Billy Bob; and Bubba. Bob also has a herd of 23 cows. Alas, poor Bob discovers that he has only a short time to live and asks his attorney to draw up his Will. In the will, Bob, Jr. is to receive 1/2 of the herd; Billy Bob would get 1/3; and Bubba, being the youngest and least responsible, would be provided an 1/8. Sure enough, Bob kicks the bucket and the boys begin to squabble. How will they ever divide the herd? No one wants a fraction of a cow. At this point, a neighbor intercedes. She is tired of the family fights and provides the boys with another cow. The herd now stands at 24. Bob, Jr. takes his half (12 cows), Billy Bob his third (8 cows), and Bubba his eighth of the herd (3 cows). 12 + 8 + 3 = 23. A-ha! The boys have now divided up the original herd according to the proportions...and the neighbor can have her cow back.
The neighbor cow is the "cattle-ist": the item which speeds up the reaction (dividing the herd) without being used up. There is a very simple reason why the math works, but it usually takes kids a few minutes to catch on. In the meantime, it gives them a great visual of how reactions can work in the body (and elsewhere).
Whew. I'm glad I let my science nerd out to run around for a little while. :) It's good to be a little different.