Numeracy fun fairs: Estimating
12 October 2009Add to My Folder
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Sweeten your maths lessons with a new take on an old funfair favourite
Counting up cakes helps to make maths fun
Making your maths lessons fun is vitally important if you want to keep yourself and your class motivated. If your class sees that you are enjoying yourself, they will enjoy themselves, too. My own experience of maths at school was of copying down endless sums from the blackboard, waiting in a queue to have them marked, then trudging back to my desk to begin my corrections. I did not enjoy maths back then, and so I always try hard to make my own maths lessons as fun as possible, to keep me interested if nothing else.
With a little ingenuity the theme of a fairground can be applied to all areas of numeracy and will add some fun to your lessons. Most importantly, it should not leave you with a mountain of marking to do at the end.
1. How many?
Curriculum links: Ma2 2a, 2c, 4b
This lesson is based on the fairground game ‘Guess the number of sweets in the jar’. You can use real sweets and share them with your class at the end of the lesson or, alternatively, any kind of chunky counters will do
You will need: An empty sweet jar or any see-through container and sweets or counting cubes.
What to do
First, it is important to establish that your class understand what is meant by ‘estimating’. For young children, ‘making a clever guess’ is a simple explanation that seems to work well. Next, explain the purpose of the game and that they will be using clever guesses or estimating to help them. In order to make a clever guess, the children will first need some knowledge to base their guesses on.
Start by helping them to recognise how many cubes there are in a small group. This may sound rather simple but the conservation of number (that five cubes will always be five cubes whether they are in a pile or stacked in a tower – Ma2 2a) can be quite difficult for some children to grasp. There are guaranteed to be some really wild guesses if all you do is ask the children to estimate how many sweets are in the jar without some prior input.
Give pairs of children a supply of cubes. Ask one child to give their partner a pile of cubes to estimate how many cubes there are, before counting and checking the number. After several attempts let them swap roles. Let the children record their estimates and the confirmed number of cubes on a mini whiteboard. Once the children have got the hang of estimating, begin the game. This is perfect for both whole-class teaching and small-group work. If you wish to do this as a differentiated activity, have a jar for each group with an appropriate number of cubes/sweets in each jar. Choose a child to be the stall holder and get them to choose a selection of children to come and guess how many sweets are in the jar. Record their answers on a chart, just like at a real fair, and at the end of your lesson, empty out the jar and see who has made the most accurate estimation.
If you only fill the jar half way, you can use the plenary to help your class calculate how many cubes would be in the jar if it was full.
2. Beyond units
Curriculum links: Ma2 1c, 2a, 2b
If your class has been working on counting in twos, fives and tens, this lesson will provide you with a great opportunity for the children to put this skill to a practical use.
You will need: Containers filled with cubes or sweets.
What to do
Either as part of the ‘How many?’ lesson (see activity 1) or separately, provide the children with a variety of containers with a different number of cubes/sweets in each one. Choose children to estimate how many cubes/sweets are in one of them.
With the children, count out cubes one by one, emphasising how laborious this method is. Model how counting in twos, fives and tens can speed things up. If your cubes/sweets are stackable put them into columns of five. Count along the column in fives, then add on any remaining cubes to find the total. Give each group of children a jar with a different number of cubes to estimate and then check. In your plenary, ask each group to share the method that they used.
3. In practice
We used this game to encourage good behaviour. Whenever individual children were seen to be sitting nicely, a cube was placed in the ‘sweetie jar’. If the jar was full by the end of the week the class were to receive a treat. The children also had to estimate how many cubes the jar contained.
We decorated a corner of the room with bunting and set up a stall with a poster advertising the game and a chart to record children’s answers. The children wrote their estimations on the chart throughout the week. At Wednesday lunchtime, we counted up 68 cubes to help them with their estimations and motivate them to ‘keep up the good work’. When we checked the cubes on Friday afternoon, there were 136 cubes. One boy guessed this exactly. Not being my most able mathematician, I asked him how he had come up with such a clever guess. ‘That’s simple,’ he said ‘I went home on Wednesday and asked my mum what double 68 was. On Thursday morning I wrote my estimation on the chart before anyone else could’. Not quite the answer I was looking for but clever stuff anyway!