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Doubling and Halving

 

Objective - To halve quantities (up to 20). 

 

 

Number blocks video (5 mins) to introduce concept of doubling and halving. 

 

https://www.bbc.co.uk/iplayer/episode/b08q4jkq/numberblocks-series-2-double-trouble

 

 

Finding half of an amount is like sharing or dividing it by two!  Watch the video clip from Numberblocks to help you understand how we halve numbers.  You will see that halving and doubling are opposites.  Using some pasta or counters, can you have a go at halving?  Ask your grown up to give you a small number to halve.  Do you notice there are some numbers you cannot halve?  We call these odd numbers!  What happens if you double a number when you have halved it?  You will notice you get back to the number you started with!  

 

Let’s have a go at halving numbers using spots on ladybirds to help us.  (Activity)

 

 

To practice doubling and halving you could have a go at this game too!

 

https://www.topmarks.co.uk/Flash.aspx?f=dartboarddoublesandhalves

Doubling

 

Objective – 1. To double and halve numbers to 20. 

 

What did we learn about doubling and halving yesterday?  Can you tell your grown up how to halve a number?  What do you do? 

 

Think about how to double numbers.  Remember you are adding the same thing twice.  Watch the ‘Ladybird doubling powerpoint’ to help you.  Now have a go at drawing the same number of spots on each side of the ladybird to double the numbers to 20. 

To help you practice doubling and halving, why don’t you have a go at the game you played yesterday. 

 

 

https://www.topmarks.co.uk/Flash.aspx?f=dartboarddoublesandhalves

Measuring and comparing

Objective:  measure lengths in cm

 

You will need a ruler and a plain sheet of paper.  Mr McGregor loves gardening and this year he has entered a competition to grow the tallest sunflower.  He plant 4 seeds.  They all grow but they are different heights!  Use a ruler to show how tall the sunflowers are.

 

Sunflower 1 = 10 cm

Sunflower 2 = 15cm

Sunflower 3 = 7 cm

Sunflower 4 = 22cm

 

After you have created a beautiful picture and labelled the sunflowers growing in his garden write down statements comparing them.

Which is tallest?

Which is shortest?

How much taller is 4 than 1

Etc

Can you use greater than and less than symbols to compare them <  >  ?

 

Arrays

Objective: use arrays to solve multiplication

 

Arithmetic/Mental starter:

Counting the beats of the drum in multiples of 2, 5, 10

 

Explain that Mr McGregor has been harvesting his veg patch- I wonder how many crops he grew?  What is a vegetable patch?  How are they usually planted- rows and columns…

 

Explain that we can use this idea to help us solve multiplications.  Briefly discuss multiplication to confirm understanding of operation.

Write ‘array’ and discuss what is means.  Work through the first of Mr McGregor’s problems creating the array together.  Challenge Y2 pupils to apply commutative law and represent array in a different way.

  • Can you create arrays to match the multiplications and use this to solve the problem?
  • Count in multiples
  • Apply the commutative law- what do you notice?
  • Can you create a division?

 

Activities

Y1- create veg arrays to match multiplications and then apply commutative law

Y2- as above plus division problems  to show the inverse.

Serve it up…

Objective- to solve division problems by sharing

Mr McGregor has had a super crop this year.  He shares out the fruit between the plates.  This is called division.  Can you share the fruit equally?  Y2 children think of other numbers of plates that you could share the fruit between equally.

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