1.2 Number sentence

Mathematics

Meet bonny and tommy

Educator section

Memorandum

p. 1: When you begin with operations, make the learners aware that the four operations (addition, multiplication, subtraction and division) involve only two different processes:

Two processes Together Separate

This includes concepts like: Add togetherJoinAltogether Take awaySeparateHand out/Divide

Four signs + x _ ¸

differentgroups equalgroups differentgroups equalgroups

Look at schematic representations

+12 + 14 = 35 -26 - 12 = 14

x5 x 3 = 15 ¸30 ¸ 3 = 10

The more the learners see this representation, and hear the explanation, the better they will understand and be able to apply it when solving problems.

The learners must understand the commutative property of addition

(3 + 4 = 7 and 4 + 3 = 7 ) and multiplication ( 2 x 5 = 10 and 5 x 2 = 10 ), but they need not know or use the words “commutative property”.

p. 2: The learners must understand the associative property of subtraction

(9 – 4 = 5 and 9 - 5 = 4 ) and division ( 10 ¸ 2 = 5 and 10 ¸ 5 = 2 ).

p. 3: Learners must first experience with concrete objects how the answers to the subtraction operations can be checked: return what you have taken away and if you have the number you began with, you know your answer is correct. Later this can then be done in writing.

Encourage them to check regularly and later they will do it automatically.

Leaner section

Content

Activity: number sentence [lo 1.9]

• Bonny has read 3 books and Tommy has read 4 books. Together they have read 7 books.

Number sentence: 3 + 4 = 7

Let’s have Bonny and Tommy change places:

Number sentence: 4 + 3 = 7

• The numbers on either side of the + sign can change places without the answer changing!

• Do the same with:

• Mom gives Bonny and Tommy 9 apples. Bonny takes 4 apples. There are 5 apples left for Tommy.

Number sentence: 9 - 4 = 5

• Now let’s give Tommy’s apples first:

Number sentence: 9 - 5 = 4

The numbers on either side of the = sign can change places.

Watch 9 - 4 = 5

carefully! 9 - 5 = 4 Now do the same with:

• Tommy cannot remember how much money he had in his purse this morning. He knows that he bought fruit for R5 and he now has R3 left. Help him. How much did he have this morning? ____________________________________

• Bonny and Tommy want to know if their subtraction number sentences are correct. We can help them to check their sums.

Number sentence: 9 - 4 = 5

Check! Put everything you took away and everything that was left, together again. If you have the same number that you started with, your calculation is correct.

• Now do the sums and check your answer every time:

Assessment

Learning Outcome 1: The learner will be able to recognise, describe and represent numbers and their relationships, and to count, estimate, calculate and check with competence and confidence in solving problems.

Assessment Standard 1.9: We know this when the learner performs mental calculations involving:

1.9.1 addition and subtraction for numbers to at least 50;

1.9.2 multiplication of whole numbers with solutions to at least 50.