A short instructional video by Rob Langman explaining how to interpret remainders in word problems, focusing on when to round down (full groups only) versus when to round up (to accommodate everyone). Two worked examples are used: 35 sweets packed in boxes of 8 (4 full boxes, remainder 3 → round down) and 415 people traveling with 50-seat coaches (8 coaches remainder 15 → need a 9th coach → round up). The video includes classroom guidance on age-appropriate methods (bar models, pictorial counting).
Chapters
Hi, my name's Ben, and in this video we're going to be showing you how to interpret remainders in a word problem. Specifically, we're going to be looking at two contexts where we round up and when we round down. Okay, here's our word problem. Sweets are packed in boxes of eight. Innis has 35 sweets. How many full boxes can she pack? And here, the key part is the full boxes. Now, if I were teaching this as an introduction to bar models, I'd maybe start this with year two or perhaps year three and keep the numbers simple. It's really important that the numbers we deal with here are nice and easy, so the children get a good grasp of how to model it out, rather than starting with harder numbers. So we've said that the four boxes part is key. And I would draw four boxes like this, and then we would look at the eights, and if you need to have it as a number multiplication grid as well, just to help the children with the 8 times table, it'll be really useful. So in the first box we have eight, because the pop in boxes have eight. And underneath I'm going to put the number eight there. On this one it'd be another eight. And two eights are 16. And this box is another eight, which is 24. And in this box are another eight, which equals 32. It's really important that they see that each box represents eight sweets and the four boxes are 32. And getting the children to articulate that in a number sentence is really useful. So four eights equal 32. But then we go back to the question. She has 35 sweets, so the children will add on and they'll realise that there are three sweets left over. So we come back to the question, how many full boxes can she pack? The answer is four. It's four full boxes with the three remainder. So that's the context where we round down. The next question is a little bit trickier. And this would probably be more upper juniors. And this is a question that typically children will get wrong or will make a mistake on, which is fine. We just need to unpick it. 415 children and adults are going on a school trip. Coaches seat a maximum of 50 passengers. How many coaches will a school need to book again? To draw this out pictorially is a really clear way. So here we've got our coaches and each one is 50. And then we can count up, and we can count up in 50s. So 50, 1001-502002-50300, 350. 400, and then we're left with 15 as our remainder. Now, this is the question where I said that we need to round up, because it's how many coaches will the school need to book? If we just took eight coaches, there will be 15 people left behind. So that's where we need to get a ninth coach. So 415 divided by 50 equals 8 with a remainder of 15. And as I said, this is a context where we need to round up. So it would be nine coaches. And that is how we can look at the two different contexts of rounding up and rounding down.
