This content was created by Rob Langman. This content was uploaded by Rob Langman. This is a YouTube educational video titled "Greater Depth in Decimals" (created 2024-04-04) featuring presenters Zoe and a second instructor (labeled SPEAKER B). It is a teaching resource about decimal number understanding and assessment: comparing 3.19 vs 3.4 using place-value charts and placeholders, addressing common pupil misconceptions, and explaining the multiplication example 2.7 × 5.21 by demonstrating Harriet's strategy of counting decimal places (converting to 27 × 521 = 14,067 then dividing by 1,000). The video emphasizes reasoning, place-value understanding, and includes suggested activities to assess pupils' depth of understanding.
Questions this video answers
14,067
Three digits after the decimal (three decimal places)
Chapters
Hi, I'm Zoe and in this video.
We'Re going to be looking at greater depth problems that you can use to assess your pupils knowledge and understanding of working with decimal numbers.
Here's our first problem at first might.
Appear quite simple but it's the explanation that we're looking for here, the reasoning behind it. So which is smaller, 3.19 or 3.4?
Problems like these are ideal to address.
Those misconceptions and if we're asking pupils to give reasons it really can let you see exactly where they're at. So for example, some of the misconceptions we might see, pupils might say that's 3.19 and 3.4 19 is bigger than 4. Therefore 3.19 is bigger.
As we can see here.
If we put them into our place value chart. 3.19, 3.4.
We've got a gap here. We're going to put our placeholder in.
And what we can see now using our place value we've got nineteen hundredths.
And forty hundredths clearly showing that 3.4.
Is bigger than 3.19. So 3.19 is the smaller number. Again really getting pupils to understand this is key to them working with decimals really successfully. Especially, especially when we come on to look at money later on. Okay, let's look at our next problem. Again working with Quite complex decimals, 2.7 times 5.21.
We've got a strategy here that Harriet says works. She says there are three digits altogether.
After the decimal points. So she just puts the decimal point in the answer to leave three digits after it.
Does this always work?
Why does it work? And explain your answer.
So, so the first thing Harriet's going.
To do is 27 times 521.
Let's have a look. By doing 27 times 521 we see the answer 14,067.
What has actually happened here?
So if we have a look at.
What Harriet has done.
So she has done.
2.7 to 27.
She'S multiplied by 10 5.21 to 521, she's multiplied by 100. So in effect she's multiplied her answer by a thousand.
We put this into here and with their knowledge of place value, of multiplying, moves our digits up, dividing moves our digits down.
We are then going to divide our answer by, by a thousand, therefore moving.
Three places down our place value chart.
So that is why Harriet's strategy works.
It's really useful to ask the pupils this to really get to the depth of explanation that you want so they feel really secure with their place value. And there are two activities that you can use to assess pupils understanding of working with decimal numbers and really establish that knowledge of where they're at.
