3.8 Adding and subtracting  (Page 2/2)

It might help them to draw the diagrams.

The decision to make use of carried numbers is left to the educator.

First supply paper shapes for dividing into tens, so that the learners may discover for themselves that tenths , like thirds and fifths, have to be calculated and measured. It is not simply a matter of folding and folding again as in the case of a ½ and a ¼ .

Guide them to discover that they, by first obtaining fifths , can divide each fifth down the middle to obtain tenths .

Discuss symmetrical shapes with the learners. Let them identify symmetrical objects in the classroom. They should complete the drawing after this exercise.

Leaner section

Content

Activity: adding and subtracting [lo 1.8, lo 1.9, lo 2.2, lo 2.4]

• These are Bonny and Tommy’s secret recipes for adding or subtracting 9:

• Find your own recipe for adding or subtracting 99 :

• Count forwards in 9’s :

785 794 _____ _____ _____ _____ _____ _____ 857

834 843 _____ _____ _____ _____ _____ _____ 906

• Count backwards in 9’s :

1000 99 1 _____ _____ _____ _____ _____ _____ 928

843 834 _____ _____ _____ _____ _____ _____ 77 1

• Count forwards in 99’s :

36 1 35 _____ _____ _____ _____ _____ _____ 828

1 71 270 _____ _____ _____ _____ _____ _____ 963

• Count backwards in 99’s :

1000 90 1 _____ _____ _____ _____ _____ _____ 208

826 727 _____ _____ _____ _____ _____ _____ 340

• Do you know:

How many legs do 120 giraffes have? _______________________________

How many trunks do 345 elephants have? ____________________________

How many horns do 342 buck have? _______________________________

How many legs do 452 ostriches have? ______________________________

How many tails do 674 monkeys have? ______________________________

How many tusks do 260 elephants have? _____________________________

How many eyes do 85 zebra have? _______________________________

How many wings do 333 birds have? _______________________________

How many fingers do 40 baboons have? ______________________________

How many feet do 21 tortoises have? _______________________________

• Use your own method to solve these problems:
• A farmer has 125 ostriches. For 3 days, each one laid one egg. The farmer sold 108 eggs. How many eggs are left over?
• There are 12 lions. Each one eats 5 chickens per day. How many chickens do we need to feed the lions for 10 days?

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 1.8: We know this when the learner can perform calculations, using appropriate symbols, to solve problems;

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

Learning Outcome 2: The learner will be able to recognise, describe and represent patterns and relationships, as well as to solve problems using algebraic language and skills.

Assessment Standard 2.2: We know this when the learner copies and extends simple number sequences to at least 1 000;

Assessment Standard 2.4: We know this when the learner describes observed patterns.