Section 4: Working with weight

Transcription

1

2 Contents Section 4: Working with weight 3 1. Doing practica work in groups 3 2. Introducing units to compare weights 5 3. Being resourcefu 6 Resource 1: Simpe baance 7 Resource 2: Pupi instructions for estimating and comparing weights 8 Resource 3: Pupi instructions for weighing activity 9 Resource 4: Traditiona weights used in Ghana 9 2 of 9 Friday 23 September 2016

3 Section 4: Working with weight Key Focus Question: How can you teach the measurement of weight using practica methods and inexpensive resources? Keywords: standard units; grams; kiograms; practica work; baances; extension; differentiation; groups; demonstration Learning Outcomes By the end of this section, you wi have: heped pupis deveop their understanding of weight by using practica activities; estabished pupis understanding of the need for and use of standard units for weight; expored different ways to organise your cass. Introduction When exporing weight with pupis, it is important to use a ot of practica, hands-on activities in the eary stages so that they are abe to buid up menta modes that wi hep their understanding in ater stages. In this section, you wi pan ways to introduce your pupis to the concept of weight by foowing three stages: comparing weights of two or more objects by hoding them at same time; estimating and measuring the weight of objects using non-standard units such as stones; measuring and comparing the weight of objects using standard units. Centra to this work is the use of simpe baances that can be made from cheap and readiy avaiabe materias (see Resource 1: Simpe baance). For advice on coecting materias, see Key Resource: Being a resourcefu teacher in chaenging conditions. 1. Doing practica work in groups Estimation is an important ski in both mathematics and science. Simpe baances (which can be made with very modest resources) aow pupis to approach measuring and estimating weight through practica investigation. You may ike to make simpe baances and pan and carry out these activities jointy with a science teacher in your schoo. This wi hep pupis see the ink between subjects. Case Study 1: Estimating weight Mrs Bankoe in Uganda was on a teachers course at her oca district offices. As part of the day s esson on numeracy, the faciitator tod the foowing story to them. Then she asked 3 of 9 Friday 23 September 2016

4 the teachers what they thought the girs knew and what woud they do next with these pupis if they were in their cass. Two girs, Nkechi and Looi, were discussing the quantity of popcorn in two packets, A and B, which ooked the same shape and size. Nkechi picked up the packets one after the other and was surprised that B fet heavier than A. She tod Looi that B appeared to be heavier than A. Looi decided to put the two packets in the two pans of a simpe baance (see Resource 1). She observed that, on the scae, packet B went down and so B is heavier than A. Nkechi was right. The teachers worked in pairs, devising activities that encouraged estimation of heavier/ ighter, then using a baance or scaes to test their ideas. Each pair tried their esson out with their casses and reported back next session. Mrs Bankoe found that her cass enjoyed the esson but that she did not have enough different objects for the pupis to use (for advice on coecting objects, see Key Resource: Being a resourcefu teacher in chaenging conditions). She said that next time she woud spend more time coecting objects and she woud use smaer groups of four to six rather than over ten in each group. Activity 1: Comparing weight You wi need five simpe baances (see Resource 1) to carry out this activity and five sets of common objects e.g. stones, bas, tins, botte tops etc. that coud be used with the baances. These can be coected from around the schoo. Write instructions for your pupis on the board (see Resource 2: Pupi instructions for estimating and comparing weights) and show the cass what you want them to do using any two objects. Give two objects to two pupis and ask them to estimate which object is heavier. Now ask a pupi to test their idea out by putting the objects on the pan. Ask them which is the heaviest object, and why they think so. Organise your pupis into five groups, giving each group a set of objects and a baance. Ask pupis to find which object is heavier by estimating its weight and then by using the baance. (See Key Resource: Using group work in your cassroom.) Ask them to fi in a tabe of their resuts to share with the cass to see if everyone agrees. You coud chaenge oder or more abe pupis to see if they can order their objects from heaviest to ightest before testing. They coud use a tabe ike the one beow. How coud they test their answers using the simpe baance? 4 of 9 Friday 23 September 2016

5 2. Introducing units to compare weights When deveoping an understanding of the idea of weighing, it may be usefu if nonstandard units are used to measure first. If pupis compare and contrast weights against non-standard unit botte tops or beans they wi quicky understand this is not sensibe, as the weight of different botte tops and seeds vary. When pupis understand the need for a common unit, the introduction of standard units ike grams or kiograms may be better understood. Case Study 2: Using a standard unit to measure Lizzy, a primary schoo teacher, fet that having taught her pupis how to use a simpe baance to compare weights of objects, they shoud now compare the weight of any object with that of a given chosen standard object. She assembed different objects and seected dry beans to be her chosen measure. Working with the whoe cass and using the baance, she asked two pupis to pace an object on one pan and put enough beans on the other unti it baanced. They counted the beans for each object and recorded their resuts. Next, she used some onger beans and weighed the same objects and recorded these resuts. She taked with the cass about the difference in numbers between the two kinds of bean and how difficut it was to compare the weight of different objects if one person used one set of beans and the other used the bigger beans. She asked them to think what they might do for the next esson. Activity 2: Data presentation Before doing this activity, read Resource 3: Pupi instructions for weighing activity and coect together the foowing resources (enough for your size of cass): simpe baances; 5 of 9 Friday 23 September 2016

6 objects of simiar weights to use as measures (e.g. botte tops and beans); objects of different weights to measure (e.g. sma bottes, tins or stones). You coud just coect enough for one group and have groups taking turns to do the activity whie the others do different work. Write the instructions for the groups on the board and expain what they have to do (see Key Resource: Using group work in your cassroomfor ways to organise your groups). At the end, ask them how it was different using beans or botte tops to measure the weight, rather than just comparing pairs of objects. Note their answers on the board. Ask if they think this is a fairer way to measure. Ask pupis to ist the objects in order from heaviest to ightest is this harder or easier than before? Why? 3. Being resourcefu The previous activities shoud have shown your pupis that standard units of weight are needed because without these it is not possibe accuratey to compare or know how much something weighs. This next part expores how you can introduce terms and deveop their understanding of kiogram (kg), and gram (g) (1,000 grams = 1 kiogram). You may want to bring bags of sugar, rice or other oca products sod in bags to cass, to show their weight is recorded in grams or kiograms and for pupis to fee the actua weights. You coud make some mock ones by fiing pastic bags with sand or stones to the correct weight. If you can, borrow a pair of scaes to do this. If you do not have access to caibrated weighing scaes or weights at schoo, it may sti be possibe to make approximate measurements of weight using your simpe baances and some everyday objects that have their weight on them to test other bags against. Once your pupis are confident at weighing in grams and kiograms, you can move on to heping them understand how to convert one to the other. Case Study 3: Using homemade standard units Mr Sereto wants his pupis to estimate, measure and compare weights of objects in grams and kiograms. He asked permission from a secondary schoo science department to use their baances to make bean bags weighing 100 g, 50 g and 10 g (using different cooured coth for each weight). He asked some of the parents who work in the oca sewing shop to hep him sew severa sets for his cass. He demonstrated the weighing of objects in grams using the improvised weights and a simpe baance, and then asked pupis to weigh objects to the nearest 10 g, and record their resuts in a tabe. Object Weight 6 of 9 Friday 23 September 2016

7 The cass were very enthusiastic and weighed neary everything they coud find in the cassroom. Mr Sereto istened to their tak as they weighed and was peased to hear them using the correct terms easiy. Key Activity: Weighing in grams Before the esson, coect a number of objects that have their weights shown tinned or packet foods and other goods (you ony need the wrapper, not the whoe good). Try to have enough to give each group of pupis at east two or three abes. It woud aso be good to have some abes for weights in kiograms as we as grams. Ask groups to write down the name of the product, and its weight ensure that they incude the correct units (grams or kiograms). They coud do this by using the actua bags and putting them in order on their tabe. Pupis coud arrange and rearrange the packages by weight from highest to owest or owest to highest or sort into groups, e.g.: 0 250g; g; over 500g. Then ask pupis to convert each weight from kiograms to grams or vice versa. When they have finished, ask each group to swap their sheets with another group and they can check each other s answers. Remind them that 1,000 grams = 1 kiogram. Discuss with your pupis why they might need to be abe to convert weights in their everyday ives. Dispay their work on the wa to show each group their achievements. What did the groups earn, and how do you know this? You coud ask them to te you what they think they have earned. Resource 1: Simpe baance Teacher resource for panning or adapting to use with pupis These are simpe baances you coud make to hep pupis compare weights. To make a simpe baance you need some string, two pastic pots or ids, two sticks and a base. Fix the sticks as shown in the diagram so the cross stick is abe to move freey. Cut six equa engths of string 3 each to attach the pastic pots or ids to either end of the stick as shown in the diagram. Pace the objects to be compared in the pots or ids one in each pot or id. 7 of 9 Friday 23 September 2016

8 Resource 2: Pupi instructions for estimating and comparing weights Teacher resource for panning or adapting to use with pupis 1 One member of the group picks up and fees the weight of two objects, e.g. a stone and a bean, one after the other. Which fees heavier? Compete the tabe beow. 2 Another member now uses the baance to compare the weights and competes the tabe 3 Repeat this for a the objects, comparing two objects at a time, aowing each member of the group to participate. 4 Pin your tabe on the wa and ook at each others resuts. Objects Which fees heavier Which weighs heavier on baance the ba and a bean the ba the ba a bean and a stone the stone the bean a bean bag and a stone 8 of 9 Friday 23 September 2016

9 Resource 3: Pupi instructions for weighing activity Put the object to be weighed, e.g. a mik tin, in the eft scae pan of the baance. Pace one bean in the other scae pan. Which is heavier? Add more beans, one at a time, in the right scae pan unti the two sides baance. How many beans do you need for this? Repeat, using botte tops instead of beans. Repeat 1. and 2. for each of the objects to be weighed. Record your observations in the form of the tabe beow. Left Right Left Right Object Number of Beans Object No. of Botte tops Find out how many botte tops weigh as much as ten beans. Find out how many beans weigh as much as ten botte tops. Resource 4: Traditiona weights used in Ghana Background information / subject knowedge for teacher Traditiona Akan weights Eephant, Bird with body in Knot, and Caw (accessed 25/06/07) Return to Numeracy (primary) page 9 of 9 Friday 23 September 2016