Posters, adverts and the media make use of graphs to illustrate mathematical information. This data can be presented in many forms, and it is important that you are introduced to a variety of representations while you are at school.
a. Pictograph Ask your friends, ‘What is your favourite colour?’ Represent each friend with a face coloured with their favourite colour:
b. Block graph Each friend can be represented in the display by a square:
c. Bar graph Instead of each friend being displayed by an individual face or square, the whole group can be shown by a bar. If this graph is drawn on squared paper it is easy to find out how many squares have been joined to make the bar:
d. Spike graphs Now change the bars to lines:
e. Point graphs Now you are going to record only a point, which is like the tip of the spike, instead of a line. Points are positioned according to their relationship to each of the two axes (vertical and horizontal):
f. Pie Chart Have a look at this Pie Chart. The size of the sectors are used like the bars in a bar chart. Each slice is a part or fraction of the whole circle:
a. Survey of foot sizes Now try making a survey of your own. Firstly you have t collect your information. Go round your family and friends to measure their feet without their shoes on. Record each foot size and tally each measurement as shown below:
Make a Tally chart: (size of foot in mm)
b. Make your own surveys Make a survey of your own. Collect information, and then make a tally chart and a graph. Here are some suggestions for your survey:
c. Road census An investigation on the traffic that passes your house, or nearby, can be interesting. Your survey will include: Lorries, vans, cars, motorcycles, bicycles and pedestrians. It is best to do your census during a set period of time, say from 8.30 to 9.30 a.m. Make sure that you use a good ‘tally system’. Usually the counting is done in fives. On the 5th count a mark across the first four is made:
Your road census can be developed into a block graph:
This can then be developed into a bar chart. The quantity or in this case the number of vehicles is not so clearly represented on the bar chart. There is now a need for a scale to show the quantities:
a. Weather chart Make a simple weather chart. Use these cards to show the different elements of weather:
Each symbol represents one day. At the end of a month one can see what type of weather was more frequent. A weather chart is made. For each school day in the month, a card is placed on the chart:
b. Investigations and graphs You can make some investigations at your school or amongst your friends:
c. Ready reckoner Have a look at the next interesting graph. It shows the products for the 2x, 5x, 7x and 9 times multiplication tables. Check it to see if it works:
d. Pie charts You will learn more about Pie Charts when you get a bit older, but here is why they are called Pie Charts as they look like a pie: