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!