Monday, June 30, 2014

Bedtime Math: baking IPhones

Tonight, we talked about the daily math story/questions from Bedtime Math. Go ahead, look at the story, read the questions and come back.

I want to write about what I think of the questions, the story, and the video, but perhaps the boys' reactions are more important:

• Video: they loved it, especially the part at the end where he puts his too hot phone in the freezer. They imagined that he would keep over and undershooting the target temperature, moving the phone between freezer and microwave to alternate cooling and heating it.
• The story: read before the video, this wasn't engaging enough for them to (appear to?) pay attention. Maybe they got more out of it than it seemed as they had no doubts about what was happening in the video
• The "math" questions: Jin enjoyed them. Jate wanted to be silly instead, but he did offer some digits for the 1/3 of 15 calculation I'll describe below.
I think this is pretty typical of the bedtime math questions.  The story and video are interesting enough for 5 minutes before bed and the math questions seem to interest the boys.  Each one, though, slightly bothers me as the math questions are basically arbitrarily imposed on the story.  For example, why do we care about comparing those temperatures, why do we care about adding one minute to the cooking time, and does batter really shield the phone in the way the last problem assumes? I guess this last one goes onto my curiosity list as item 40.

Maybe I shouldn't be so critical: this story about Big Ben had more related questions.

Field report
Wee and Little Ones
Way too easy for Jin, he answered immediately.  As a result, we'll never know how Jate would have found them, but I think too easy for him, too.

1/3 of 15 minutes: Jin
I had to help explain that 1/3 of 15 minutes involved splitting 15 into 3.  Before calculating, we talked about what halfway would be (he guessed 7 minutes, but knew it wasn't quite enough).  He then asked for half of 7.5 to get 1/4 of the time through as a way to bound the answer to the actual question.  Great strategy, but did he really know what he was doing?

From there, Jin asked us to collectively produce 15 fingers so he could parcel them into 3 groups.  At first, we got a mixed collection of hands and feet (thanks Jate!) By chance, or stealthy guidance from father, eventually we three each contributed one hand, so dividing into 3 groups was obvious.

The sky's the limit
I was surprised that Jin really took note of the initial 2 minutes safety window for the phone and included it in his thinking.  I guess this sort of residual has been emphasized to him in past problems, but I don't recall it figuring prominently in anything we've discussed together.

He eventually got the answer 20 ounces with the strategy of guessing an amount, figuring out if it works to protect the phone for the required cooking time, then adjusting.  I helped him keep track of the pieces of the question, which seemed fair since we were doing this without paper or pencil.