Foundation- Subtraction 7/11/17
We have been singing subtraction songs. We sang ‘5 Little Ducks’ and ‘5 Little Speckled Frogs’. We kept taking frogs and ducks away and then we decided what the number sentences would be.
Can you use your fingers to work out these subtraction problems?
Can you think of any other subtraction problems?
Today the children revisited some previous learning. The children of Fir class have been learning about the reason we revisited different learning to train our brain to retain information.
Did you know you have to do something or hear something 500 times to retain it?
The children looked at adding and subtracting today by playing one of their favourite games – Nice and Nasty. The children are able to challenge each other to create the biggest number through adding or the smallest through subtraction.
Maple Class welcomed the challenge of trying to solve some subtraction problems today in our numeracy session. Avoiding the easier, more boring route, we decided to embrace our new interesting challenges!
Armed with bead strings, we worked systematically to solve the subtraction problems. Sliding the beads across the string, we ‘took away’ and ‘subtracted’ from 10.
What did you notice? Explain the pattern we spotted to someone in your family.
10 – 0 = 10
10 – 1 = 9
10 – 2 = 8
10 – 3 = 7
10 – 4 = 6
10 – 5 = 5
10 – 6 = 4
10 – 7 = 3
10 – 8 = 2
10 – 9 = 1
10 – 10 = 0
To make things even more interesting, some of us then started to look at what happens when we ‘take away’ and ‘subtract’ from 20 in the same systematic method.
What will the next number sentences look like? How can you prove you know this?
20 – 0 = 20
20 – 1 = 19
20 – 2 = 18
20 – 3 = 17
20 – ? = ?
20 – ? = ?
Year Three are working hard on subtraction. We are using various methods to solve problems up to at least 3 digits.
Counting back on a number line
Today, we have been continuing our learning of the four operations with a special focus on column subtraction. We have been able to regroup, use formal methods for subtraction and solve problems in context.
Here is another video we have been using, to show the children a range of subtraction strategies. We have explored lots of different methods to subtract and discovered our personal favourite.
Some of us prefer to jump back along a number line, in tens and ones. For others, we prefer to partition the two digit number and take away the tens first and then take away the ones, in number sentences.
Which method will you use? Why do you prefer that strategy? How could you explain it in a different way?
61 children take subtraction outside! Yes, Palm Class and Apple Class took their subtraction skills outside today. We collaborated together to create blank number lines, to help us subtract two digit numbers from two digit numbers.
First, we wrote the biggest two digit number in our number sentence at the end of our blank number line. After that, we partitioned the other two digit number into tens and ones.
We jumped back in tens to start with and then ones. We recorded our landing numbers each time. Some of us noticed quicker methods to jump back, by jumping 1 big jump instead of smaller jumps. Finally, we counted all our jumps back, to calculate the answer.
96 – 39 = ?
73 – 58 = ?
51 – 27 = ?
How many jumps would you need to make to calculate these subtractions on a blank number line? Which numbers would you land on for each jump? What are the fewest jumps required?