![\"Kite\"](\"\/content\/images\/2014\/Aug\/kiteposter.jpg\")
<\/p>\nIn my Year 9 textbook, the start of the chapter on area and volume starts with a “review” of areas from past years. And by that, I mean it says something along the line of “you should remember these formulas from Year 8,” then proceeds to list the formulas for the areas of various shapes.<\/p>\n
Uhhh, no. Wasn’t going to cut it. I’m not doubting the importance of remembering the formulas, but the book makes a huge assumption that all students understood the formulas completely last year, and just needed a quick reminder before they jumped back into, I don’t know, completing boring lists of questions from the book I guess.<\/p>\n
Instead, I didn’t just want my class to remember the formulas, I wanted them to explain how they work, where they come from. I broke the class into groups and assigned them different shapes. They had to produce a poster demonstrating how we can discover the areas of their shape using other shapes – ideally this would be something of an informal proof. Here’s some of the results:<\/p>\n
This group didn’t end up showing the formula, but they did show the general idea behind the proof. With a bit more prompting, I’m sure they would have gotten to the formula.<\/p>\n
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This group showed two different methods for proving the area of a parallelogram, which is awesome. I especially like that the one using the rectangle didn’t involve any words. I think my students are slowly getting around the idea of using mathematics instead of English to communicate.<\/p>\n
![\"Parallelogram\"](\"\/content\/images\/2014\/Aug\/parallelposter.jpg\")
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I made this one. I thought the circle was a bit beyond my class, but I still wanted a poster for it.<\/p>\n
![\"Circle\"](\"\/content\/images\/2014\/Aug\/circleposter.jpg\")
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Rather than trying to explain my poster myself, I showed the class this video from Minute Physics<\/a>:<\/p>\n