Posts Tagged ‘Ratios and Rates’

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I’ve been using this video for over a year now in presentations on the revised program of studies. My intention in showing it is to demonstrate a problem with number sense in our society in general.

I have spent a year making fun of the Verizon people’s mathematical abilities. Today, however, I am ashamed (and a little amused) to admit that someone in the employ of the same district I work for has made the exact same error. An astute EPSB math teacher sent this flyer my way today.

Show your students this flyer. Ask them what they wonder about.

I would have them calculate how much 100 pounds of books will cost. See if they make the same faulty assumption that I believe the person creating this flyer must have made. I can’t believe they really intend to sell the books for half a cent per pound. If that is true, I’m rushing right over on Friday to get my 100 pounds of books for 47 and a half cents.  I’ll even give them 48 cents and let them keep the change.

Give your students extensions. How many pounds of books could they get for $20 at this rate? Would all those books fit in a car? What about for $100?

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I saw this episode of Seinfeld a couple of days ago.  Now that my WCYDWT radar is finely tuned, I realized that it would be a good clip to show in a Math 10-3 class in the unit on rate and ratios.  I know it’s a little dated (who would use a Wizard now?), but it’s still one of my favorite shows.  Click on Morty to play the clip.

The one question kids need to ask will be apparent to them, but the math will be tricky for Math 10-3 students.  In the end, it’s still not a particularly compelling problem, but maybe this is a better way of presenting it to students.

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Here’s a WCYDWT for Alberta’s Math 10-3 on Ratios and Rates.

This fish, a 60 pound sturgeon, was recently caught and released in a small self-contained pond on a golf course near the Red Deer River.  When local biologists heard about the catch, they decided to investigate.  They surmise he (or she) came into the pond when the river flooded five years ago, and then spent the next five years feeding happily on the stocked trout.  Since sturgeon are endangered, it was important to return him (or her) to the river, which they were able to do.

This story reminded me that about ten years ago, I was fortunate enough to be present when a team of biologists surveyed a cutthroat trout population on a remote mountain stream.  Biologists typically use a method called electroshock fishing to stun fish so they can be tagged and released. They had a boat with a generator on it and a long metal prod which they poked around in the water.  When the current got near enough to a fish, it would be momentarily stunned, and float to the surface.  The biologists then weighed, measured and tagged the fish before returning it to the stream.  Any fish that had been previously tagged had its number recorded and it was again weighed and measured.  It was a humbling experience to see that there were actually abundant numbers of fish in that stream, because I had been unable to catch any earlier that day with my fly rod, but I digress.

I have used the story of watching the biologists electroshock fish several times in my classes as a ratio problem and asked students determine the population of fish in that stream.  Sometimes I gave my students the number of fish tagged on the first day, and then the number of tagged fish caught on a second run of the same stretch of river later on.  Other times (and probably a better problem), I had my students design an experiment to predict the population of fish before providing them the actual numbers.

Red Deer Advocate story about the fisherman who first caught the fish

Red Deer Advocate story about the biologists capturing and releasing the fish back to the river

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