Addition & Subtraction 2

Learning content:

Uses appropriate terminology to describe, and symbols to represent, mathematical ideas MA2-1WM

Selects and uses appropriate mental or written strategies, or technology, to solve problems MA2-2WM

Checks the accuracy of a statement and explains the reasoning used MA2-3WM

Uses mental and written strategies for addition and subtraction involving two-, three-, four- and five-digit numbers MA2-5NA

Task Three

Complete these worksheets using Jump strategy.

Task Four (teacher - these can be adjusted to 2-digit numbers where required)

Use the jump strategy to solve the following problems.  Show your working.

1.  Sara has 253 books.  Andrew has 338 books.  How many books do they have altogether?

2. Mrs Parker bought 175 erasers at the beginning of the school year.  Mrs Ibbott also bought 242 erasers.  How many erasers does Year 3 have?

3. Simon picked 279 mangoes from one tree in their garden.  Jackson picked 248 mangoes from another tree.  How many mangoes did they end up with?

4. Jason was sorting out equipment for his teacher.  He found one thousand and seventy popsticks in one drawer.  Amanda found two thousand and thirdy-four popsticks in another cupboard.  How many popsticks does the class have altogether?

5. Steven played 24 games of soccer in term one, then he played 18 games in term two, followed by 33 games in term 3, and none in term four  How many games did he play throughout the year?

6. Nancy has 836 marbles.  She gave Tom 588 of her marbles.  How many marbles does she have left?

Task Five

Write your own problem using addition or subtraction and give it to a classmate to solve (using 2 digit or 3 digit numbers).

Revise Split Strategy

Today we are going to revise the Split Strategy for addition.

Watch through the two videos below to remind you of how to use the Split Strategy.

Task Three

Have a go at some of these split strategy worksheets or task cards.  Remember to keep your numbers in the right columns. 

If you are doing the task cards, please show your working in your scrapbook, using split strategy.  

Answers to task cards on teachers notes page.

Task Four

Create one 2 digit addition problem, two 3-digit problems, and two 4-digit problems for yourself.  Then solve them.  Give your work to a partner and get them to check your answers.

Task One

When you look at number stories, it is important to think carefully about whether you need to add or subtract (take away).  

If the story is asking you to put two or more things together, then you have to add.  

If the story is asking you to find the difference between two items, and see how much less it is, or how many more you need, then you have to subtract (take away).  

Lots of people find it hard to understand what finding the difference between two numbers means, so let's have a look at how to explain this, and try one or two examples.

Then try the second activity where you have to sort questions out into an Add or Subtract column.  Cut out each square and glue it under the Add heading or the Subtract heading in your scrapbook.

We are learning to use the Compensation Strategy

Today we will look at another addition strategy.   Your teacher will work through the learning below with you.

Here are a few questions to practise together as a class. 

Example: 14 + 9 =  14 + 10 - 1

23 + 9

36 + 9

25 + 8

When you are confident with these examples your teacher will give you a worksheet from below to complete.

Revise what was done in Thursday's lesson and continue practising compensation strategy.  Complete any worksheets that need finishing.

Using Compensation for subtraction 

Now you can watch the videos below to see a way you can expand your use of Compensation strategy.

Teacher - use whichever of these videos you feel will be most beneficial to your students.

Task Five

Work out the Would You Rather challenge below.

Task One

Have a go at this challenge.

Task Two

When we are buying something in a shop, and don't have the right amount of money, we give the shopkeeper a larger amount of money.  For example, if you are buying a packet of cards that costs $7, you might give the shopkeeper $10.  Then the shopkeeper needs to give you some money back to be fair.

Often we do this by counting up from the $7 until we get to $10, and we discover that the shopkeeper would need to give us $3 back.

Counting on to the next dollar makes it a lot easier when we have to work out the change for the number of cents we need to get back.

If you buy lollies for 35c and you pay for them with 50c, the shopkeeper will often count on to work out your change.

The lollies cost 35c, so the shopkeeper will give you back another 5c (which adds up to 40c) and then another 10c (which makes it add up to the 50c you gave them).  So now you can see that you would get 5c + 10c in change = 15c change.

Task Three

Complete these worksheets where you have to work out the correct change to be given.

Practise counting up from the cost of the goods to the amount of money you gave the shopkeeper, and work out the change you deserve that way.  You could draw or write each coin in the space as you go.

There are a number of sheets below that your teacher will choose for you to complete.

Task Five

Watch this thinking activity.

The Snack Machine - thinking stimulus for change giving

*Money – value of coins and notes plus change giving

Task Two

Catch up on any activities that you have not finished.