Comparing: same and different
To compare means to look at two or more things together. Ask two questions: what is the same? What is different?
Use the same points for both things. If you compare a bus and a train, check speed, cost and number of seats for both. Do not check speed for one and colour for the other.
A simple table helps. Write the points in the first column and one thing in each next column.
Try it
Pick any two fruits at home. Write 3 things that are the same and 3 that are different.
Classifying: one rule, many groups
To classify means to sort things into groups. The sorting needs a rule, such as shape, colour, size or use.
A good rule has three features. Every thing fits in one group. No thing fits in two groups. The rule is easy to say in one line.
The same things can be sorted in more than one way. Six solids can go by shape (cubes, spheres, cones) or by colour (red, blue). A new rule gives new groups. Neither is wrong. Choose the rule that helps your goal.
Try it
Take your school bag items. Sort them by use, then by size. Notice how the groups change.
Relating: linking ideas together
To relate means to find a link between ideas. The most useful links are:
- Cause and result: rain, so plants grow.
- Part and whole: a wheel is part of a cycle.
- Before and after: seed, then plant, then fruit.
Draw an arrow from the cause to the result. A web of arrows is a concept map. Careful: two things that happen together are not always cause and result. Ice cream sales and sunburn both rise in summer. Hot weather causes both. Ice cream does not cause sunburn.
Using all three tools together
In a group project you can use all three. First classify your notes into groups. Then compare the groups. Last, relate them with arrows to show the full picture.
Example: a study on school lunches. Classify lunches as home-made or bought. Compare cost and health. Relate cost to what children choose. Now you have a clear answer with reasons.
Key formulas and definitions
- Compare = find what is same + what is different (use the same points for each)
- Classify = choose one rule, then every item goes to exactly one group
- Relate = cause โ result, part โ whole, before โ after
- Correlation is not always causation
Worked examples
1. Compare a cycle and a motorbike. Give one same and one different point.
Same: both have two wheels. Different: the motorbike uses fuel, the cycle uses leg power. Both points are checked for both vehicles.
2. Classify these: apple, carrot, banana, potato, mango, onion. Choose a rule.
Rule: grows above or under the ground? Above: apple, banana, mango. Under: carrot, potato, onion. Every item is in one group only.
3. Sort 10 coins by size, then by year. Will the groups be the same?
No. A new rule gives new groups. A small old coin and a big old coin are together by year but apart by size. Pick the rule that fits your question.
4. Relate: a student sleeps 4 hours and gets low marks. Is sleep the cause?
It may be one cause, but we need more proof. Check other causes, like how much the student studied. Compare many students with different sleep hours before you say cause.
5. Make a relation chain for the water cycle using 4 words.
Sun heats sea โ water vapour rises โ clouds form โ rain falls. Each arrow is cause to result and the chain ends where it began.
Common mistakes
- Comparing different points for each thing, like speed for one and colour for the other.
- Sorting with a rule that is not clear, so one item fits two groups.
- Thinking there is only one correct way to classify. Different rules give different groups.
- Saying A causes B only because they happen together. Look for other reasons first.