10. Strategies calculation up to 100
58 + 26 =
Solve
Solve the problems
and write down your
calculations.
85 – 32 =
Show the way you
find your answer!
43 + 35 =
72 – 37 =
16. The strategies used by the learners of
Elim Primary School in Windhoek
In grade 3:
Counting one-by-one,
Stepwise addition and subtraction/ Stringing,
Splitting,
Digit algorithm
In grade 4:
Stepwise addition and subtraction/ Stringing,
Splitting,
Digit algorithm
In grade 5:
Digit algorithm
18. Strategie 1: Counting one-by-one
Teaching materials
All kind of counting materials
19. Strategie 2: Stepwise addition and
subtraction/Stringing
45 + 28 =
Joan has read 45 pages in
her book.
Today she reads 28 pages.
45 + 20 = 65
65 + 25 = 70
70 + 23 = 73
20. Strategie 2: Stepwise addition and
subtraction/Stringing
84 – 27 =
I cut 27cm off a ribbon measuring 84 cm.
How much is left?
21. Strategie 2: Stepwise addition and
subtraction/Stringing
50 – 36 =
I spent 36p in a shop.
How much change did I
get from 50p?
36p + ____p = 50p
Counting on using a number line is
particularly useful in calculating
change.
‘Shopkeepers strategy’
29. Which strategie do you choose?
N$ 92
A book with 84 pages.
You are reading at the
bottom of page 37.
How many pages still to
read?
N$ 69
The black t-shirt costs
N$ 92 and the grey t-shirt
costs N$ 69.
How much more expensive
is the black t-shirt?
30. The basic strategies:
1 Stepwise addition and subtraction/
Stringing
Starts with flexible counting
The ‘large number line’: 10 – 20 – 30 – 40 –
50 – 60 – 70 – 80 – 90 – 100
The ‘small number line’: 1 – 2 – 3 – 4 - 5 – 6
- 7 – 8 – 9 – 10 – 11 – 12 - ….- 33 – 34 – 35
– 36 – 37 – 38 – 39 - 40- etc
Use of the empty number line as a ‘notation
scheme’ and ‘paradigm’
31. The basic strategies:
2
Splitting/ column calculation
Starts with place value
Use of the 10-frames as a ‘paradigm’
Use of the ‘column notation scheme’
emphasises the place value
34. Discussion
What materials are you using now in
computation up to 100?
What strategies do you teach in computation up
to 100?
Do you see a relationship between computation
up to 20 and computation up to 100? Please,
explain.
36. Studies
How does it start?
Which steps for the learners to make in the
learning trajectory?
Which teaching materials are usefull in the
teaching trajectory?
Which notation schemes do the learners use?
What are the learning outcomes in this
teaching learning trajectory?
37. Please, make the materials yourself
Use the materials and discover the possibilities to
teach mathematics with these ‘easy to make’ teaching
materials!
Jaap Griffioen – j.griffioen@hr.nl
Jaap de Waard – j.de.waard@hr.nl
38. The 100-caterpillar
100
Choose two different numbers between 0 en 100,
Put these numbers in order in the first and the
second part of the caterpillar,
Make the number in the next part by adding the
two previous numbers,
The number in the fifth part must be 100!
39. 75-game
5
10
15
20
25
30
35
40
45
Player 1
Player 2
Rules of the game:
Take a turn to a number,
Choose from the numbers 5, 10, 15, 20, 25, 30, 35,
40, 45,
Each number can be chosen only once!
Do you have three numbers which together have 75?
You are the winner!