d58207ae42f531b732e01933a517f1ba.ppt

- Количество слайдов: 74

Imagine you work at an orchard and have 27 apples… And they’re in a basket Ok, but your apples are Green…

1 27

Your boss at the orchard tells you to put the green ap into bags that hold three apples each… = 1 2 3 If you had x-ray vision, this is what you’d see in this bag… I promise…

How would you figure out how many bags you would need for the 27 apples? 1 4 2 3 5 6 6 bags is only enough for 18 apples…

One way to solve this problem would be to take 3 apples out of the basket and put them in one bag. To start: 27 - 3 = 24 apples left in the basket… And one bag with 3 apples… 1 2 3

1 24

You could repeat: take 3 more out of the basket: 24 - 3 = 21 apples left in the basket… 1 1 2 3 And you would have 2 bags holding 6 apples in total… 2 4 5 6

1 21

Can you figure out how many times you could take 3 apples out of the basket before the basket is empty? What’s your answer?

If you said 9 times, you’d be correct… 9 8 4 7 3 6 5 2 1

How can you show all this mathematically? Because 9 groups of 3= 27 9 X 3= 27 or 27÷ 3 or 3 27 The last two both mean 27 divided by 3

Work on this one!!! You have a giant container of ice cream and you’re going to make quadruple scoop cones for your friends. The container has enoug ice cream for 28 scoops. How many quadruple-scoop cones can y By the way, 4 A quadruple scoop cone has how many scoops of Ice-cream

Is this Mr. R. when he was a kid? 4 3 2 1

What does the question look like mathematically? Division is sharing or grouping a number into equal parts For example 6÷ 2 = 3 equal groups with 2 in each group 2 3 6 But let’s get back to the ice cream…

We have 28 scoops of ice cream and we need to find out how many equal groups of 4 we can make. How can we write a math sentence to represent this? Is it 4 x 28? Is it 28 ÷ 4 Is it 28 - 8? Is it 28 + 4 Is it 28 - 4 Which one of these is used to share 28 into equal groups of 4?

Sometimes to solve a division problem like 28 ÷ 4, we we may use a lot of subtraction… 28 - 4 = 24 1 cone 24 - 4 = 20 2 cones 20 - 4 = 16 3 cones You can continue subtracting 4 scoops of ice cream until there are none left…

Besides subtraction, we could draw a diagram or use manipulatives for help…

Here we use a diagram to divide the 28 ice cream scoops into groups of 4…

Our multiplication facts (and fact families) can really help in div How many ice cream scoops would you use for 4 cones?

If 4 cones = 16 scoops How many cones would it take to reach 28 scoops?

What number (of cones), multiplied by 4 (scoops of ice cream) = 28 scoops in all? 5 cones x 4 scoops = 20 scoops 6 x 4 = 24 scoops 7 x 4 = 28 scoops

Finally, you can use fact families to help with division… If 7 x 4 = 28 Than 28 ÷ 4 = 7

Now it’s ice cream time!!!

Work on this one!!! You have a container of ice cream and you’re going to mak triple scoop cones for your friends. The container holds 18 scoops. How many triple-scoop cones can you make? By the way, 3 A triple scoop cone has h scoops of ice-cream

Part 2

What in the world would you do if you had 771 apples in your basket? ? ? We would need a bigger basket… First of all, you would need a bigger basket…

Still not 771!!!!

And still not at 771!!!

Anyway, your boss wants you to put 3 apples in each bag again wants you to keep track of how many bags you used. = 1 2 3 Can you estimate how many bags you would need for 771 apples?

Do you think you would you need more than 100 bags for the 771 apples? Why?

I’m tired of apples, I want ice cream!!! fourt h

I guess you could figure out how many bags you would need by taking away 3 apples at a time 771 -3 = 768 -3 = 765 -3=762 -3 -3=759 -3=756 -3= 753 -3= 750 But that would take a long time, wouldn’t it?

What if you took 300 apples out of the basket all at once? Can you figure out how many bags you would need to hold 300 apples?

If you said 100 bags, you’d be correct… Let’s put those 300 apples in 100 RED bags….

How many apples would you have left in your basket?

Well, 771 -300 = 471 Apples left

Uh-oh, you have 100 red bags of apples, (with 300 apples in But you still have 471 apples left in your basket… I think you NEED more bags!!!

Hey, maybe you can fill another 100 bags? What do you think? Why?

Sure you can, because you have more Apples apples left…. 300

So you tell your boss you have 471 apples lef and you need 100 more bags to hold 300 more apples.

This time, you put the 300 apples in BLUE bags…

Now you have 200 bags that are holding 600 apples… 100 RED bags and 100 BLUE bags

How many apples would you have left in your baske More than what’s in this basket!!!

If you thought: 471 apples minus 300 apples you’d be correct That’s equal to 171 app

What will you do with those 171 apples that are still in the basket? No, you can’t eat them- 171 apples will upset your stomach, besides, you have to sell them so you can buy your teachers big birt gifts… Can you fill another 100 bags with apples Why?

Just how many bags can you fill with your 171 a

Can you think of any multiple of 3 tha less than 171? Let’s try some… 3 x 90 bags =270 apples That’s more than 171 apples 3 x 80 bags= 240 apples Nope, still too much

How can you figure out a multiple that is less than 171… Yup, it’s a great time to use those mental math multiplication skills!!!

How about 3 x 50 = 150 That’s less than 171… You can take apples 150 out of the basket….

Let’s make 50 more bags of 3 apples eac We’ll use green bags this time!!

Okay, let’s review… You took out 300 apples, and put them in 100 red bags…

Then you took out 300 more apples, And put those in 100 blue bags…

Then you took 150 apples from the baske and put those in 50 green bags… How many bags have we used together? 100 red + 100 blue + 50 green

250 bags in all !!!

But you still have apples in our baske What are you ever going to do? NO YOU CAN’T EAT THEM!!!

First of all, how many apples are left? You had 171, and you took out 150…. Figure that out…

If you said, 21 apples, you would be correct…

Can you find a multiple of 3 that’s less than, or equal to 21? ? ? Think multiplication tables…

10 x 3 = 30 apples Too many…it’s more than 21 apples you 5 x 3 = 15 apples You could use 5, because you do have 15 ap but is there a better choice? What do you think?

Oh, so you thought of a multiple t will give you exactly 21 apples? Sure, 7 x 3 = 21

So you need 7 more bags to hold the remaining 21 apples…Let’s use purple bags…

Do you have any apples left in your basket? No, not in this basket I think you can tell your boss that you’re done!!

But your boss wants to know how many bags you used altogeth

Let’s count our bags… 100 red bags 100 blue bags 50 green bags 7 purple bags 257 bags altogether!!!

Let’s count our apples… 100 red bags 300 apples 100 blue bags 300 apples 50 green bags 7 purple bags = 257 bags in all 150 apples 21 apples 771 apples in all

So 771 divided into groups of 3 = 257 With a remainder of 0 apples!!!

Now you can eat an apple!!! BUT WAIT!!!!!!

What does all of that look like as a division prob 771 ÷ 3 or 3 771

Let’s do this on ‘paper’…Please get a blank sheet out… Let’s think about how you subtracted apples… First we subtracted 300 apples from 771 using 100 red bags 100 bags 3 771 -300 471 left…

Then we subtracted 300 more apples from the remaining 471 using another 100 blue bags… 100 bags 3 771 -300 471 -300 171 left…

Then we subtracted 150 apples from the remaining 171 using 50 green bags 50 bags 100 bags 3 771 -300 471 -300 171 -150 21 left…

Then we subtracted 21 more apples using 7 purple bags 3 7 bags 50 bags 100 bags 771 -300 471 -300 171 -150 21 -21 0 left

Add up the bags and that’s 257 bags!!! Can you solve this one using the same met 3 633