# Lesson video

In progress...

Hi, welcome back to your unit on number sense.

Now today's lesson I am really looking forward to.

We are going to be recognising the value of each digit in two digit numbers.

We're going to be playing a really fun game today together.

Let's get started with our learning.

Here we have our lesson agenda for this lesson.

We're going to start off by looking at the big picture before moving on and playing a dice game together.

We're then going to do some problem solving before you finish the lesson with an independent task and quiz.

for this lesson you will need a pencil, a piece of paper, a ruler, and a dice or online dice.

So pause this video if you need to find any of those resources, and then let's get started.

Here we have a picture of Cambridge University.

Now during the summer holidays, lots of the students like to earn a little bit of extra pocket money by taking other students out on their boats or punts.

Here we have a chart which shows us four different students.

So we have Amit, Serena, Tom, and Fabian, and how many students they each take out on their punt.

We can see Amit has taken 23, Serena has taken 37, Tom has taken 27, and Fabian has taken 33.

Who took the most passengers? How do we know? Pause this video and have a think.

Having a look at the four different students and the number of students, we can use dienes to represent how many students they each took.

So Amit took two tens and three ones, which is 23.

Serena took three tens and seven ones, which is 37.

Tom took two tens and seven ones, which is 27, and Fabian took three tens and three ones.

Have a look who took the most.

We can see that Serena took the most because she took three tens and seven ones.

Having a look at these two lovely little moles, which digit has the greater value, the ones digit or the tens digit? How do you know? Pause this video and think.

When we're deciding if a number is larger, or greater, or smaller, we tend to look at the tens first to determine whether the number is greater or smaller.

So we are going to play a dice game together now.

I have got my dice here, and the aim of the game is to get the largest number.

So what I am going to do, I'm going to roll my dice.

And I have rolled the number five.

So I need to decide if my five is going to go into my tens column, or if it's going to go into my ones column.

Because remember, I want to make the greater number.

Now five is a tricky one because five is slap bang in the middle of zero and nine.

I'm going to put it into my ones, because I think I could actually roll a greater number.

I'm going to roll again to see if I can get a greater number.

Wish me luck.

Oh no, I rolled a one.

My one has to go into my tens column, so I rolled only 15.

I bet you can beat that.

Pause this video and have a go.

Brilliant, shall we go again? Let's have another turn.

Let's see if I can win this time.

Oh, so this time I've actually rolled a six, so I'm going to put my six into my tens column, because that's the highest number that I can actually roll on my dice.

Let's roll again.

And this time I rolled a one, so the number you need to beat is 61.

I bet you can't do it.

Pause this video and take a turn.

Great job, now we're onto my favourite part of the lesson.

We're going to be doing some problem solving.

Let's do it together.

Here you can see I have a grid with the numbers one to 36.

I also have some clues.

So let's read the clues together.

Number one: the number is odd.

Number two: the tens digit is greater than one.

Number three: the tens digit is greater than the ones digit.

And number four: the sum of its digits is equal to three.

So let's get started with clue number one.

The number is odd.

Now I know all my even numbers end in two, four, six, eight, or zero, so I'm actually going to cross out all of the even numbers.

Clue number two: the tens digit is greater than one.

So unfortunately, all the numbers which don't have a tens digit or the tens digit is one are going to get crossed out.

Number three: the tens digit is greater than the ones digit.

I can know that two is actually less than three, so that one's getting crossed out.

The same for 25, 27, 29, 33, and 35.

So now I'm left with two numbers, 21 and 31.

The sum of this special number's digits is equal to three.

Three add one is equal to four, so I'm going to have to cross that one out, aren't I? So I'm left with the number 21.

You're going to be doing some problem solving and you need to use the clues to solve which number the answer is.

Pause this video and good luck.

Brilliant, well done.

Let's go through it together.

The number is odd, so all of those even numbers are getting crossed out.

The tens digit is greater than one, so unfortunately again all of those numbers without a tens digit or the tens digit is one are getting crossed out.

The sum of its digits is less than seven.

So here you're going to do some addition.

For example, two add one is equal to three, so we're actually going to keep 21.

We're going to cross out 27, 29, and 35.

Clue number four: the tens digit is greater than the ones digit.

Here we're going to be crossing out 23, because two is less than three.

Crossing out 25 because two is less than five.

We're also going to be crossing out 33, because well, three is equal to three.

Then we have two numbers left, which is 21 and 31, and it is the greater of the two numbers and we are left with the answer 31.

Well done, give yourselves a massive pat on the back.