Data Handling
Class 8 · Mathematics
5 ideas in Class 8 Mathematics, explained in plain words, with games and quizzes to practise.
Choosing and Reading Graphs
Part of: Graphs and pie charts
A pictograph uses symbols, a bar graph uses bars of equal width whose heights show the values, and a double bar graph puts two bars side by side to compare two sets of data. A pie chart shows how a whole is shared among parts.
Why it matters. Graphs turn lists of numbers into pictures we can compare quickly. Choosing the right graph for the data is a daily skill, used in news, sports and school projects.
Try it in two minutes
- Collect the number of steps taken by each family member in a day and draw a bar graph on paper.
- Ask: who walked the most? What is the difference between the highest and lowest?
- Draw a second bar next to each for another day and say what changes.
Try at home. Ask your child to draw a pictograph of the fruits in the kitchen, using one symbol for 2 fruits.
Reading Pie Charts
Part of: Graphs and pie charts
A pie chart is a circle split into sectors. The whole circle is the total, and each sector is a part of it. A sector that is half of the circle shows 50%, and a quarter shows 25%. The angle at the centre tells how big the part is: 360 degrees is the whole.
Why it matters. Pie charts are used in news, reports and budgets. Children who can read them can see at once which part is biggest and how much of the whole it is.
Try it in two minutes
- Draw a circle and cut it into 4 equal pieces like a pizza. Ask: what fraction is each piece? How many degrees?
- Colour two pieces and ask what percentage that is.
- Ask what 3 pieces would be.
Try at home. Ask your child to read a pie chart in a newspaper or book and tell you the biggest part.
Drawing Pie Charts
Part of: Graphs and pie charts
To draw a pie chart, find each category's share of the total, then multiply by 360 degrees to get the angle of its sector. For 20 out of 80, the share is 1/4 and the angle is 90 degrees. All the angles add up to 360, which is a good check.
Why it matters. Drawing a pie chart joins fractions, multiplication and angles in one task. The check that the angles add to 360 teaches children to verify their own work.
Try it in two minutes
- Ask your child to list how many of 12 sweets are of each of three types.
- Work out the fraction for each, then the angle, using 360 for the whole.
- Check that the three angles add up to 360.
Try at home. Ask your child to find the angles for a pie chart of a day: 8 hours sleep, 6 hours school, 10 hours other.
Random Experiments and Outcomes
Part of: Chance and probability
A random experiment is one whose result cannot be predicted exactly in advance, like tossing a coin or throwing a die. The possible results are called outcomes. If every outcome has the same chance, the outcomes are equally likely.
Why it matters. Understanding randomness stops children from thinking that a coin 'is due' for a head. It is the base of probability and of reading statements like 'there is a 30% chance of rain'.
Try it in two minutes
- Toss a coin 20 times with your child and keep a tally of heads and tails.
- Ask: are the two counts exactly equal? Are they close?
- Do a second set of 20 tosses and compare the two sets.
Try at home. Ask your child to list all the outcomes of spinning a spinner with 4 coloured parts.
Probability of an Event
Part of: Chance and probability
When every outcome has the same chance, the probability of an event is the number of outcomes in the event divided by the total number of outcomes. For a die, the probability of an even number is 3/6, which is 1/2. A probability of 0 means it cannot happen and 1 means it is sure.
Why it matters. Probability helps children make fair choices and understand weather forecasts, games and polls. It is also a neat use of fractions.
Try it in two minutes
- Put 3 red and 2 blue buttons in a bag. Ask: how many outcomes? How many are red?
- Write the probability of red as a fraction.
- Draw 10 times with replacement and compare the result with the fraction.
Try at home. Ask your child to find the probability of getting a number less than 5 when a die is thrown.
What your child will practise
- Choosing and Reading Graphs: Number Sort (Sort It Out)
- Drawing Pie Charts: Ocean Quick Fire (Quick Fire)
- Probability of an Event: Ocean Puzzle (Clue Puzzle)
- Random Experiments and Outcomes: Candy Quick Fire (Quick Fire)
- Reading Pie Charts: Mission Control Quest (Collect the Answer)
- Quiz: Choosing and Reading Graphs (8 questions)
- Quiz: Drawing Pie Charts (8 questions)
- Quiz: Probability of an Event (8 questions)
- Quiz: Random Experiments and Outcomes (8 questions)