Why you should still have an analog clock

Teaching ACT Math this semester is actually really fun- I get a chance to dabble in teaching all kinds of math. The main difficulty with it is that I teach 9th graders. Who are very interested in college, but the ACT is just so far away…

I try to incorporate sample problems into the Warmup/Do Now/Bellringer/pickyourflavor. Today’s was an especial gem that led to a lot of rich conversation.

Screenshot 2014-01-26 10.46.37

We talked about drawing a picture and then some kids admitted they were stuck. One student volunteered that she split the clock into 4 90˚ chunks, and then split that in half to get 45˚ but she still wasn’t sure of the answer. Another student took that idea and said he split the 90˚ into 3 chunks since there were 3 hours so each hour is 30˚. Since we were looking for 1 o’clock, he reasoned, it is one 30˚ angle (choice B)

Then another student volunteered that instead of splitting into 4, she split the 360˚ circle into 12 and got 30˚. She had a hard time coming up with a reason for why it was 30 and not some other multiple of 30 when I had asked her earlier, though.

Finally, I introduced the idea of proportions (1/12 = ? / 360) and showed how it was just like what they had done.

We were really riding a high as a class, one girl was like everyone in here is so smart, and I was like, maybe I we can just take this gig a little further. So then I asked them what time each of the other answer choices would show. They told me 45˚ would be 1:30 because “it’s a whole 30˚ plus 15˚, which is 1 hour plus half an hour”. This was my proudest moment of the day today- maybe my constant number sense modeling (a la Jo Boaler) is finally taking root in their freshman brains!


One comment

  1. If you may not think that you simply have the time to do it, make enough time. If you never know anyone who can help, then maybe look for a club or group related in your passion, often these are free or little cost.

Learning is having new questions to ask (thanks, Chris Danielson).

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