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# Market maths: pounds, kilograms and proportion

These photos are all 1024 by 768 pixels and you can use them on the projector and on worksheets. Just right click and select View Image to see each image in its full glory.

I took them at Birmingham Food Market a few weeks ago for a metric revision class. I'll use laminated prints of the full resolution images next year with work cards I think just to save on the colour printing.

Interesting as it has price for half a pound but for a whole kilogram. Students could check all the equivalences are correct as a starter.

You can just about see four price tags in this one image. Two are priced per pound weight but do not have costs per kilogram - students could provide one. The 7 for £1 and the 5 for £1 suggest proportion questions, but also questions along the lines of

"Algernon wants equal numbers of oranges and nectarines and the trader won't split the quantities. What is the smallest number of each he can buy and how much will it all cost?"

Actually, the traders will sell you a few but hardly anyone asks. The wording of the tags (Red Globe for grapes, and the fruit name missed off the cherries) might help students develop vocabulary.

Loving those apostrophes. Who would have thought that a kiwi fruit was half the cost of a lemon? Students could practice writing sentences using fraction words.

Stories about Algernon shopping for broccoli and lemons. Comparisons between images could lead to percentage calculations.

"Algernon is shopping in the market. One stall has lemons 6 for £1, and another has lemons 5 for £1. What is the percentage price difference between the cheapest and the most expensive?"

I hope this question will cause disputes about which to take as 100%. The challenge is to be very clear about what you are comparing to what. Students challenged to write sentences like "5 for £1 is X percent more expensive than 6 for £1".

Check the price per kilogram. Estimating: how many onions in one pound weight? Might buy some and use the kitchen scales in a class.

These Majorcan Mids need a metric price!

Check that the price per pound weight is consistent with the price per kilogram.

If I use these next year, I'll post the worksheet here. I might just get some cheap card and some permanent markers and get the students making price labels and discussing the pricing. Wholesale market next, then I can do some of the profit questions.

Keith Burnett, Last update: Sat May 24 2014