40 Million Times A Year

I sometimes find myself surprised by my students' response to lessons or activities. This week in my 4th Grade Math class I have been experiencing one of those times. I began the week of reviewing the multiplication algorithm with the following prompt:

How many times does your heart beat?

...in an hour?...in a day?...in a month?...in a year?...in your life?

While I expected some interesting discussion about how the set up the problem, I did not expect the incredible level of discussion before doing a single calculation. And not by just the one or two über insightful students, but by the entire class. This simple prompt to initiate practice of a mechanical skill with real data has turned into a incredibly rich investigation. My students have engaged the school nurse, as well as outside experts via Twitter.
After presenting the prompt above, my students launched into an animated half hour long discussion, considering a wide range of associated questions:

• how many times does it beat in a minute
• How do we know how fast it beats?
• It matters if you're exercising or still.
• It depends on what you're doing.
• It might matter what you're eating.
• If you're running it beats fast.
• It depends how long you live.
• The months have different numbers of days and there are leap years.
• Does gravity matter?
• Does your mass/weight matter?
• Does our heart slow down while sleeping?
• Does fatigue or dehydration effect it?
• Does age matter?
• The rate is always changing.
• We need an estimate.
• Does your height matter?
• We need to get resting pulse, then exercising, get an average, something in middle.
• We need a rate between the highs and lows.
• Everyone will have a different answer.
• Does respiration rate matter?

As the discussion started to wind down, I asked for suggestions of what to do. Again, the idea of findinsg a median resting pulse was suggested. Not by name, but in concept: "Some people will have a slower pulse and some will be faster. We need to figure out what the middle [pulse rate] will be." We arrived at a median resting pulse of 76 beats per minute.

For homework, I asked them, "How many times will your heart beat in 2013?" And that brings us to the title of this post. Take care of your hearts my friends, it is a busy muscle.


The investigation has continued to build. I will share more in my next post.

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