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July 23, 2013

Angle of 5:45 on an analog clock

In the geometry class the children were calculating all kinds of angles so I thought I will give a thought break and look at a place where we can estimate angles in everyday life.

I asked for the angle of 4:00 on an analog clock. I need to draw it for the kids to understand what I am talking about. Once I do I immediately got an answer obtuse angle. I realize that the only thing the children have every been asked to guess when an angle is whether it is acute, right, obtuse, straight (180'), reflex, complete (360'). I say great, now tell me what the angle is. I need to repeat myself 3 times before it sinks in that this dude wants us to tell the actual angle.

They ask for hints and I ask them what 3:00 would have been and they say 90'. I let them know that that is the hint.

It takes a few minutes to settle in, one kid gets it. He is all excited and gives the answer. I ask him to explain and he does and most of the kids don't get it. A couple of others do and they explain it quite nicely dividing the 90' as 3 sets of 30' one for each hour and adding an additional hour to 120'. Now, everyone joins in we do 5:00, 6:00, 7:00. Ok, everyone is getting it and its getting boring now. We pull it up one notch and I ask for 4:30. Immediately the smart cookie thinks he has got it, I let him know he needs to think more. He is flabbergasted, he tells me I don't even know the answer, I let him know I know how he thinks and he got 60' and he needs to think more.

I need to walk them through why its not 60' and mention that the hour clock needs to move he figures it out. Again explanation only gets across to a couple and again the couple explain it in a way that 90% of the class gets it. We try a few 5:30, 6:30, ok everyone is getting it by now.

Right then 5:45 it is! Three of them actually get it and we run out of time... 

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