Apr 28 2010
counting air
I wrote a post last term about my S2 class asking to base their lessons for the remainder of the year around the science of space. Since returning from the Easter break, I’ve been working on incorporating numeracy and problem solving into these classes.
The first time they returned to my class, there were funny looks in my direction. I rearranged the desks to create working groups and pointed towards the equipment they would use; very large measuring cylinders, some tubing and stopwatches.
The scenario I used was
You are an astronaut joining a 10-day mission on the space shuttle. NASA needs to know how much air you will need during the trip.
There was confusion. The responses included
- NASA know how much air to pack
- they give astronauts a personal oxygen cylinder
- that’s impossible
- how do you measure gas?
In other words: “Houston, we have a problem.”
If the lesson was going to go anywhere, I would need to give some hints. I started by asking where we had obtained oxygen for earlier experiments. Some pupils remembered heating potassium permanganate, probably because of the near-explosive results we had achieved that day. I had to remind them of the time we collected oxygen gas under water from a cylinder. The measuring cylinders were really just large gas jars and so we could exhale into them through a tube.
We aimed for at least one person per group to measure the volume of air they could exhale in one breath. Some pupils used stopwatches to count the number of breaths per minute and I could see that they were starting to identify a strategy to answer the challenge. More importantly, they began to explain their understanding of the problem to the others in their group and, within minutes, I had someone from each group ask for a calculator.
By the end of the lesson, and it did take around 45 minutes, each member of the class has calculated an answer and compared it with someone else. We discussed their answers and I explained that we use problem-soving methods like this in the real world. Someone said it was like a mobile phone contract, I probably showed my age when I compared it to working out an electricity or gas bill.
I wasn’t going to post about this lesson. That changed when I watched Dan Meyer’s TEDxNYED session.
Dan’s analysis of our current approach to problem solving is spot on -- I often remark to senior pupils that the question setter is leading them by the hand through a problem. In this lesson, I avoided asking
How much air do you breath in
(i) one minute
(ii) an hour
(iii) a day?
and, in doing so, the class took ownership, rationalised and shared what they were doing.
Let’s make over the problem solving we do in science as well as maths.