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**What is it?**

At MathsConf14 in Kettering I presented an idea for a set of problems that I have been using with my Year 11 class. For 12 years of my career I had been batching similar problems together. So, for example, following a sequence of lessons on Pythagoras’ theorem, I would present my students with a range of questions, set in a variety of contexts (ladders leaning against walls, ships sailing between buoys, etc) all of which had Pythagoras at their core. The problem was, those kind of questions do not allow students to identify a Pythagoras question when it is presented in isolation. So, I started creating sets of 4 problems where the surface structures are the same, but the deep structures are different- thus forcing students to think carefully about what the question is actually asking. Hence, SSDD was born, and this is a wonderful example of these type of questions.

**How can it be used?**

We use SSDD problems at lead twice a week with our Year 11s in the build up to exams. Presenting students with 4 problems which, on the surface, look very similar has provided an incredible challenge as they battle through trying to discern exactly what the question is about. Indeed, a set of questions like the ones in this wonderful resource could take a class all lesson and lead to some fascinating and useful discussions. You also get the added advantage of revising four topics for the price of one. SSDD problems could also be used for homeworks or end of topic tests, this benefiting from the positive effects of spacing. The SSDD problems revolution starts here!

My website, SSDD Problems, can be found here: ssddproblems.com

Thanks so much for sharing

Craig Barton

Download: SSDD Question Set 1

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