2.5 To measure  (Page 2/2)

Seeing that 3x and ÷ have just been done, it is easy to introduce thirds now. Give the learners loose paper shapes and allow them to fold and measure on their own, so that they can discover how it can be done. Some of the learners will know how to find sixths without any help. (Only enrichment)

The idea with the recipe is to make the learners understand that certain standard units and containers must be used, otherwise there is no chance of success with a recipe.

Let the learners mention more examples of the use of standard units in practice, e.g. petrol, milk, mixing medicines, prescriptions for administering medication, etc.

It is essential that all the different standard measuring containers and scales, as well as sand, water and objects used in measuring volume and mass , should be available in the classroom. Learners should be able to experiment every day with measuring and weighing, using standard units: litres and millilitres and grams and milligrams .

A bathroom scale is required to determine the mass of the learners.

Different methods are used for the multiplication and division calculations, but should you prefer another method and you find that the learners understand it better, it is their right to use the preferred method.

It is essential that many similar examples of the relevant number sentences be done orally before the learners are expected to complete this worksheet.

The regrouping of a hundred when adding or subtracting is now formally taught. Sufficient concrete work must be done beforehand. More advanced work where a ten and a hundred are regrouped simultaneously, should not be done at the same time. It will depend on the abilities of the group whether it should be done immediately hereafter or at a much later stage.

Whether the learners will be allowed to make use of carried numbers, remains the decision of the educator. e.g.

Learners will need a blank sheet of paper in order to calculate the shortest route. Some learners may find it difficult and may want to give up, but with a little help they should be able to do it.

A discussion on what they will see as they approach the farmstead by road is necessary before the learners will be able to draw it.

Leaner section

Content

Activity: to measure [lo 1.1, lo 1.4, lo 1.11, lo 4.5]

In order to measure accurately , we have to make use of standard units . Shorter lengths are measured in centimetres and millimetres . We can use a ruler to do this. 10mm = 1 cm

Longer lengths are measured in metres and for this we can use a metre stick, a tape measure or a trundle wheel. 100cm = 1 m

• 

  Use your ruler and measure the lengths:

• Use your ruler and draw a line 14cm long . Now halve it.
• Draw a line 12cm long and divide it into 4 quarters .
• Use the metre stick to measure two objects in the classroom that are longer than your ruler but shorter than the metre stick. Estimate first .

• Use the tape measure to measure the height of two of your friends. Estimate first .

• Use the trundle wheel to measure the length of the stoep or the corridor.
• Measure it . It is __________________________________ long.
• I was wrong by _____________________________________________

• Tommy is going to help Grandpa to make a new camp for Granny’s chickens. The new camp will be rectangular - 50m long and 30m wide.
• Measure the length of the 4 sides of this rectangle.

AD = _____________________________________________

AB = _____________________________________________

BC = _____________________________________________

CD = _____________________________________________

We discover: AD = BC and AB = CD

The two opposite sides of a rectangle are of the same length .

Thus : 2 times the length plus 2 times the width (breadth) is equal to the perimeter of the rectangle . ( 2 x l ) + ( 2 x b ) = perimeter

This is how we write it: 2 l + 2 b = perimeter

• 2 times the lengths is _________ cm and 2 times the width is __________ cm.
• The perimeter of the rectangle is _________________________________ cm.

Now Bonny and Tommy know how to calculate what length of wire netting is needed to make the camp. They only have to calculate the perimeter of the camp.

• 2 times the length is___________ m and 2 times the width is _________ m.
• 2 l + 2 b = perimeter

_____ + _____ =

• The perimeter of the camp is ____________________________________ m.
• The camp will have a wooden gate that is 1m in width. Thus Grandpa has to buy only ________________________ m wire netting.

• The rectangle has been divided into three equal parts . Colour in 1 of the 3 parts.

• Show how you will solve the problems. You may draw.

Granny baked 24 cookies. Bonny and Tommy ate ¼ of them.

How many cookies are left?

There are ________________________________________________

• Bonny and Tommy each got R12 from Grandpa. Bonny spent ½

  

  of her money and Tommy spent ⅓ of his. Who spent more?

__________________________________________ spent more.

• Tommy is 1m 37cm tall and Freddie is 1m 43cm. What is the difference between their lengths?

The difference is _______________________________________________________

• Grandpa buys a rope that is 16m long. How many 2m-pieces can he cut from it?

He can cut ____________________________________________________________

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 1.4: We know this when the learner orders, describes and compares numbers;

Assessment Standard 1.11: We know this when the learner explains own solutions to problems;

Learning Outcome 4: The learner will be able to use appropriate measuring units, instruments and formulae in a variety of contexts.

Assessment 4.5: We know this when the learner estimates, measures, compares and orders three-dimensional objects using non-standard and standard measures.