TickTockMaths

Tag: subtraction

  • Efficient Calculations : Addition and Subtraction

    Download the PowerPoint here

    I was going through my old PowerPoint slides looking at my column addition and subtraction stuff. Which was fine, I guess. But I’ve abandoned using slides for a lot of that stuff and set up examples using mathsbot’s place value counters. They’re awesome. (Although I’d like to be able to save an example for later use). I then use loads of randomly generated questions. Usually I’m a fan of writing my own questions, but randomly generated addition and subtractions, especially if you put them in a crossnumber are where it’s at.

    What I like talking about, though is efficient calculations. I’ve extracted them and made them into their own lesson here. I really believe in talking about this stuff. My year 7s will sit for ages and work out a calculation left to right without even thinking about number bonds.

    We’re sometimes so tied to hitting examable objectives that we forget this stuff can be really powerful. My ideal year 7 scheme of work would move away from these skills and move onto covering things a bit more nebulous like ‘Tricks’ or ‘Diagrams’ (drawing bar models etc) so by the time we’re in year 8, we are all efficient and able calculators. I’d also add loads of binary and bases stuff. I don’t really care that it’s not in the GCSE. Stuff can be valuable without being a examined skill in the GCSE.

  • Robert Low: Why is subtraction so hard?

    Really interesting article and worth a read

    Subtraction presents various problems to learners of mathematics, not least with the mechanics of hand calculating the result of subtracting one multi-digit number from another. But that’s not the kind of difficulty I’m interested in: I’m more interested here in the difficulties that arise when computations involving several additions and subtractions of integers are involved, or at the slightly more advanced level where algebraic computations involving several additions and subtractions are required. I’m going to take a look at what I think lies underneath the difficulty.

    http://robjlow.blogspot.com/2018/06/why-is-subtraction-so-hard.html

  • The Progression Of Addition and Subtraction

    I don’t know about you, but as a secondary school teacher I’ve not often thought about teaching some of the maths fundamentals. We assume students can already add, subtract, multiply and divide single digit numbers. Secondary teachers don’t pay enough credit to primary teachers, who have the critical job of embedding concepts like place value.

    But sometimes students come in without these skills, and I’ve always found breaking them down really difficult.

    This video is lovely It’s one of a series, talking about the progression of skills from first principles. I highly recommend all maths teachers watch them. I will certainly be trialling some of these ideas. I found the talk of five and tens grids particularly interesting.