Day 65: Random Variables and Gallery Walks
We are finishing up the introduction to Random Variables in AP Statistics today and I thought it was time for students to work together on some problems on discrete and continuous random variables including finding and interpreting the expected value and standard deviation of discrete RVs and using notation properly. Once again, I want the kids to be actively engaged in thinking about and doing the problems rather than passively watching me or another student work thorough a problem. Don’t get me wrong; there is a time and place for modeling good mathematical techniques, but we are past that today.
So I gave a 20 Minute Poster assignment. Groups were given 20 minutes to solve and write up a problem by applying their statistical knowledge and using good AP-level communication. Each member of the group chose one colored marker and could only write in their color on the poster. They signed their name in the same color so I could see the contributions made by each individual. Lots of good clarifying questions and discussion in making the poster: “Does a uniform distribution look like this (showing a normal curve)…then what does it look like?”, “why is P(X=3) equal zero in a continuous random variable distribution?”, “I don’t get why P(X>3) = P(X≥3) for a continuous random variable, but they aren’t equal for a discrete random variable,” and “how do we find the standard deviation if we don’t have the probability distribution given to us?”
After the posters were completed, I had students pair up using Clock Buddies…today it was their 7 o’clock buddies. Using a Gallery Walk protocol, the pairs had 5 minutes to read over and check the work on a poster that was not either of theirs, leaving sticky notes with “I notice…” and “I wonder…” comments regarding the correct application of statistical techniques and good communication. After 5 minutes, they moved to another problem and did the same. I will post the original problems and photos of their solutions on our website.
How do you use formative assessment techniques in your classes?