To measure

MATHEMATICS

Bonny and Tommy visit the farm

EDUCATOR SECTION

Memorandum Number Concept to 600 Operations: Addition – two and three digit numbers with and without regrouping of the ten. Subtraction – two and three digit numbers with and without regrouping of the ten. Multiplication – two digit number with a one digit number without regrouping the tens to 99. Division – two digit numbers divided by a one digit number without a remainder or regrouping the tens to 99. The 3× and 3÷ tables to the tenth multiple are taught. These conclude the tables to be learnt in Grade 3. Repetition and testing should be done regularly. The telling of time is very important. It is recommended that this be done classically as it requires much preparation and is immensely time consuming. The learners each need a clock to handle and can construct one out of cardboard before the lesson. In module 4 the number concept is extended to 600. Addition and subtraction calculations include two and three digit numbers. Multiplication and division calculations are done without regrouping of tens, and only up to 99. In learning 3x and ÷ up to the 10th multiple, the tables that have to be mastered in Grade 3 are completed. Regular repetition and testing are vitally important from this stage on. It is recommended that the reading of time be done with all the learners at the same time. Each learner must have a cardboard clock to use when the work is being done. Such a clock can be made from a paper plate, or the learners can be allowed to design their own clock for Technology. However, it must be ready before the reading of time is started in class. A great deal of practical exercise is necessary before the learners can complete the worksheets. Number concept is now extended from 400 to 600 and the number blocks of hundreds, tens and units, as well as the flared cards, (attached to Module 2), must still be used to promote the number concept. Give special attention once again to the 100 that must be regrouped when 300 and 500 are halved: 300 = 200 + 100 500 = 400 + 100 Counting in sixes must be done incidentally and can also be repeated on the multiples chart (Module 2). Learners must know: 1 dozen = 12. Learners must have the opportunity, and be encouraged, to say what they can deduce from the graph, what can change and what will not change, before they have to write about it. Such a discussion will give you a good indication of what the learners understand and which aspects need more attention. Learning 3x and ÷ must be done on the mat and with the use of concrete apparatus. The worksheets are only there to apply what has already been taught. Learners must get the opportunity in class, on a daily basis if possible, to take measurements with the ruler, the metre stick and the trundle wheel. The more practice they get, the more accurately they will measure. However, always encourage them to estimate first. This is enrichment work and if you find that it is too advanced, it can be done at a later stage. There may be learners who would like to accept the challenge. 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 .metre 1 2 3 4 5 6 7 8 9 centimetre 100

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. Object Estimated Measured Too much or too little

Use the tape measure to measure the height of two of your friends. Estimate first. Object Estimated Measured Too much or too little

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.