addition and subtraction. addition relate addition to combining two groups and counting on and...
TRANSCRIPT
AdditionRelate addition to combining two groups and counting
on and record in a number sentence using + and = signs.
13 + 24 = 37Record addition by: model and images
+
When the children are comfortable with this we move onto adding on
a number line.13 + 24 = 37
13
+10 +10+1 +1 +1 +1
23 33 3734 3635
Develop methods for adding two digit and three digit numbers by partitioning second number only.
246 + 37=246 + 30 = 276276 + 7 = 282
Then we develop written methods for addition of two and three digit numbers using expanded methods of recording.
375 + 67
300 70 5+ 60 7
300 130 12 = 442
Mina and Ben play a game. Mina scores 70 points. Ben scores 42 points. How many points did they score in total?T= How many points did they score in
total?
I = 70 42 +
N= 70 + 42 =
A=
Your turnMina and Ben play a game. Mina scores 35 points. Ben scores 63 points. How many points did they score in total?
T=
I=
N=
A=
There are 265 children at Hill School. 102 children have a packed lunch. 27 children go home for lunch. The other children have a school lunch. How many children have
school lunch?
Subtraction
Relate subtraction to taking away by counting back and as counting on and record in a number sentence using the – and = signs.
Subtraction not crossing through the tens boundary.
46 – 25 =
- 25 = 21
In a subtraction calculation we always write the digits of the second number, we don’t draw the image!
Once the children are comfortable with this strategy we move them
onto subtraction on a number line.
49 – 14 =
49 - 10
39
-1
38
-1
373635
-1 -1
Subtraction by partitioning not crossing the tens boundary.
48 – 32 =
40 – 30 = 10
8 - 2 = 6
10 + 6 = 16
Subtraction crossing the tens boundary using partitioning.
53 – 37 =
50 – 30 = 20
3- 7= We can’ t do this so we take one of the above tens.
13 – 7 = 6
10 + 6 = 16
10
This is the same process even when crossing through the tens barrier.
63 - 28 =
63 - 20 = 43
43 - 8= 35
Begin to record calculations in preparation for an efficient
standard method- expanded decomposition. 81
- 57 70 and 11
50 and 7
20 and 4
= 24
Problem Solving
Sita had 87p. She spent 35p.How much money did she have left?T= How much money did she have left?
I = 87p 35p left -
N= 87p – 35 p=
A=