Short instructional YouTube video (presented by Clare and a co-presenter) teaching bar modelling to solve a percentage word problem. The problem: this week's attendance is 6,348, which is 25% less than last week's. They model last week as four equal parts, note that 75% equals 6,348, divide 6,348 by 3 to find 25% (2,116), then multiply by 4 to reach last week's attendance of 8,464. The lesson emphasizes interpreting percentage language correctly and using short multiplication for SAT-style tests.
Questions this video answers
6,348
25%
2,116
8,464
Divide 6,348 by 3
Chapters
Hello, I'm Clare and today we're going to look at bar modelling and how to solve tricky problems involving percentages. So let's have a look at the actual question. We've got a number of fans at a football match and the total number is 6348, 25% less than the number who watched last week's match. How many people watched last week's match? Now, the first thing you need to check is that the children understand this is a tricky question. It's not asking us to take away 25% from the 6348. It's actually saying that this is something, that this is a number after that amount. So let's have a go at drawing that. So far I've done this week, I've drawn a bar to represent this week.
Which was 6,348 fans. There they are. So let's do last week.
And the only thing I know is that they have 25% more fans, so they have a longer bar, which is.
Going to be 25% longer than the.
Bar I've drawn for this week. So I'm going to check that I've.
Done that accurately by drawing in the other 25%.
So that's 50%, 75%, 100%. Now, you can see quite clearly that I have got 75% of last week is the same as 6,348 fans, because 25% obviously is the same as a quarter.
So I've got three quarters of last week's fans is the same as 6348 fans.
So my next thing I need to find out is how many fans make up 25%. 25% is the same as a quarter.
But I look here, I've got three quarters here. If I want to find the value of one of those quarters, I'm going to have to divide 6348 by 3.
I'm going to do that using the bus stop method.
So to do the bus stop method, I've got 6348 dividing it by three. Now, I always say to children, we start by the numbers at the beginning of the queue. So I've got threes into six, go twice. Threes into three, go once. Threes into four, go once. Remainder one. Threes into 18 will go six. I now know that 25% represents 2116 fans, and I'm going to put that one onto my bar model. I'm going to take out the 25% there and show that that is now 2,116 fans.
Now, the question asked me how many people watched last week's match?
So now, straight away, hopefully the children.
Can see I can either add up 2116 four times or do a short multiplication.
I think short multiplication is obviously the quickest method and you want to encourage.
That during SAT test tests.
So I've got 2116 multiplied by four. Six fours are 24. Once four is four, add on five, six. Once four is four, two fours are eight.
I've now got.
My total number of fans is 8464 fans.
And there we have it. That's how we can use bar modelling to solve more complex questions involving percentages.
