A short teacher-facing instructional video by Hannah demonstrating three activities to develop greater-depth understanding in subtraction for primary pupils. Activity 1 explores repeated subtraction (subtracting 4 from 845) and links it to division/four times tables to decide if 0 will be reached. Activity 2 asks pupils to arrange digits to produce the smallest possible subtraction result, using digit cards and prompting about multi-digit minus one/two-digit strategies. Activity 3 has pupils create subtraction questions that yield a given answer (324), optionally requiring a specified number of exchanges; this activity targets deep place-value and subtraction conceptual knowledge. The video includes differentiation tips for supporting pupils and extension prompts for greater-depth learners.
Chapters
Hi, I'm Hannah and in this video we're going to look at what subtraction in greater depth might look like for your pupils. We'll work through three activities which will require your pupils to reason and apply their knowledge of number, subtraction and place value. So this first question asks, if you start at 845 and keep subtracting 4, will you eventually reach 0? It's a good idea to give your pupil some discussion time. You may wish to guide their discussion by asking them, will you reach zero? How do you know this? One method might be to use a number line, so I could start at this end and subtract four. However, that will take me some considerable time. Your pupils working at greater depth might notice that repeated subtraction is the same as division. We can therefore use multiplication, the inverse of division. So we can use our four times tables. Pupils working at greater depth may notice that as we have a five in our ones column, it cannot possibly be in the four times table. So no, the answer is that we cannot arrive at zero if we continue Take away four. To support your pupils who are finding this a little bit trickier, you may wish to ask them what will happen if you use your four times tables. You may also wish to provide them with a hundred square as then they can use this to identify different numbers in the four times table. They can then see if 845 meets this criteria. Our next question asks, can you arrange these digits in a subtraction to get the smallest possible answer? Explain your reasoning. It's a good idea to allow your pupils some time, independently or in pairs, to talk about this problem. It may be a good idea to give your pupil some digit cards as then they can physically manipulate the problem and see what answer they arrive at. You may wish to assess their understanding by asking, why have you put them in that order? You may wish to support pupils who are finding this a little bit trickier by asking them what will happen if you have a three digit number. Take away a one digit number. This should help them arrive at the conclusion that a two digit number. Taking away a two digit number is the best strategy. Pupils working at greater depth should be able to reason that this is because a three digit number take away a one digit number would give you a lot smaller difference. So that is how you could approach this activity. This final activity asks you to find an answer to the subtraction calculation, which is 324What could the question have been? So to make this a little bit harder for your pupils, you may wish to stipulate the amount of exchanges required. For example, you may wish them to come up with a subtraction calculation with exactly two exchanges. For your pupils to succeed with this, they will need to have a deep conceptual understanding of subtraction, and they will also need a deep understanding of place value. So that is how you could use three different activities to support your children working at greater depth in subtraction, and these activities could also be changed to work with any operation.
