Voiceover:
In a world without maths,a land where people forgot, who will save the day?
Mr Sharma:
Errrrr, Ooooo鈥1, 2, 3, 4, 5, where鈥檚 the next box? Aww why can鈥檛 I buy them separately?
Mrs Barker:
Morning. Just the one box of pencils today?
Mr Sharma:
Yes. I mean, I think yes. Maybe I need some more. Right, there we go.
Mrs Barker:
Are you sure you鈥檝e got everything you need?
Mr Sharma:Yes, errr no, umm not sure. Err, hold on.
Mrs Barker:
Is that everything then?
Mr Sharma:
Ooo no, now that looks too many.
Mr Sharma:
I鈥檓 buying new pencils for the school but they only come in boxes of five. How do I know how many I鈥檝e got? Oooohhh it鈥檚 hopeless.
Mrs Barker:
Don鈥檛 worry.
Mrs Barker:
There鈥檚 someone we can call.
Mrs Barker:
Is he here?
Mrs Barker:I can鈥檛 see. Multiplication Boy,please can you help Mr Sharma work out how many boxes he needs so I can get out of this pencil prison.
Narrator:
This is a tricky one. First of all, what needs doing?
Mr Sharma:
I鈥檓 buying new pencils for the school but they only come in boxes of five.
Mr Sharma:
How do I know how many I鈥檝e got?
Narrator:
Hmm how can Multiplication Boy work out how many pencils Mr Sharma is buying without taking them out of the boxes and counting them?
Narrator:
Fives! Yes, I think you鈥檙e right. To work out how many pencils Mr Sharma is buying we need the 5 times table.There are five pencils in the first box.
It鈥檚 going to take a long time to draw all these pencils, so let鈥檚 use dots instead.So, 5 in the first box, 5 in the second box, 5 in the third and 5 in the fourth.
Mr Sharma:
Aha so now we count the dots, ooo that鈥檚 very clever.
Mr Sharma:
1, 2, 3鈥
Narrator:
We could count all the dots but I think Multiplication Boy has a faster way. Mr Sharma, can you count in fives?
Mr Sharma:
Errrmm maybe, I can try.
Narrator:
Multiplication Boy will help.
Mr Sharma:
1 lot of 5 is 5, 2 lots of 5 are 10, 3 lots of 5 are 15, 4 lots of 5 are 20!
Oh, that鈥檚 not enough.
5 lots of 5 are鈥25, almost there.
Mr Sharma:
Thanks.
6 lots of 5 are 30, that鈥檚 it.
Mr Sharma:
Woohoo.Oh no.
Oh no no no no noooo.
Now there are 6 dots in each line, but there are only 5 pencils in each box.We鈥檒l have to start again. Awwww.
Narrator:
Hold on Mr Sharma, I think Multiplication Boy knows what鈥檚 happened here.
We have 5 lots of 6 but if we turn the paper round鈥e can see 6 lots of 5, both equal 30.
Mr Sharma:
That鈥檚 what we had before!
Narrator:
The number of dots in the array hasn鈥檛 changed. 5 groups of 6 make 30, 5 x 6 = 30. And 6 groups of 5 make 30, 6 x 5 = 30.
Mr Sharma:
It鈥檚 the same answer, ha hoo! 6 x 5 = 30 and 30 is just the number of pencils I need for the class.Amazing, thanks Multiplication Boy.
Now where did that lady go? Lady on the till? Helloo鈥? I鈥檓 ready to buy my pencils鈥
Mr Sharma:
Yoohoo! Hello?
Video summary
Mr Sharma needs to buy new pencils for the school but they only come in boxes of 5.
How does he know how many he鈥檚 got? His attempts at guessing leave Mrs Barker in a sticky situation.
This sounds like a job for Multiplication Boy! Luckily, our hero in a world without maths knows what to do.
He speeds up Mr Sharma鈥檚 counting by showing him how to use arrays to multiply.
Multiplication Boy and Mr Sharma also explore the commutative law of multiplication to solve some counting confusion.
Will Mr Sharma be able to work out exactly how many pencils he鈥檚 buying? Will Mrs Barker manage to escape her pencil prison? And will the children ever actually get their new pencils?
Teacher Notes
Children could continue the learning with multiplication problems based on the story.
For example: Mr Sharma has got all the pencils he needs, but he also wants some paper. He has 3 packets of paper, and in each packet there are 10 pieces of paper. How many pieces of paper is that in total? What is the calculation?
How can you show this as an array? Children could use counters, pegs or images to create arrays to help them to solve similar multiplication problems.
Some children might begin to explore the commutative law of multiplication by writing out the related multiplication calculations once they have created or drawn an array (e.g. 3 x 10 = 30 so 10 x 3 = 30).
This clip will be relevant for teaching Maths at KS1 and KS2 in England and Wales, and First and Second Level in Scotland.
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