Jan 212012

Really, I found a use for the boxes of old scantrons I have in storage! I didn’t think of it myself, though. It came from here.

Provide each student with a scantron sheet and ask them to guess which would be the correct answer to the first question, if you were unable to see the question.. Talk about the percentage of the students in the class which would have guessed correctly. Extend this to two questions and so on. You can then talk about the math behind probability.

In AP Statistics, as well as the Algebra 3 class I teach, we do binomial probability. It is very abstract, and difficult material. For the Alg 3 course, we incorporate Pascal’s Triangle, as well as the combinatorials, and it becomes a very interesting lesson. But there are still always learners who can never figure out what I mean when I ask:

Now suppose you are taking a 12-question multiple choice test with four possible answers to each question. You need to pass the test in order to get ‘un-grounded’ for that crap you pulled last weekend.

  1. If you are totally guessing on every question, what is the probability that you will get a passing grade of at least 60% on the test?
  2. Suppose all those minutes of studying pay off and you are able to eliminate one answer for each question. Now what is the probability that you will pass the test and get to go out on Friday?

Yes, this is a real question I ask in Alg 3. The fact that you need 8 out of 12 questions right really stumps the learner, because they try to use that instead of the (.25)(.75) probability required.

But if they actually had a scantron in front of them, would they do better? I don’t know, having taught the material in Alg3 several weeks ago (before Christmas break). But my AP Stats class will be doing the binomial distribution this week. I am going to try it as an introduction. We can then extend the formula to the normal model afterwards.

I will report back what I find out. [which means that one of my goals this year is more active blogging and sharing. I have said that before, but never give up!]

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