Sorting Objects into Groups

1Summary 重點摘要

Sort objects by colour, shape or size — sorting is the first step of statistics.

2Vocabulary cards Vocabulary

3Step by step Steps

1. Step 1: Pick one featureThe first step of sorting is to choose one rule: by colour, by shape, or by size? Use one feature at a time so the groups stay clear. Example: a box of blocks sorted by colour puts all the red ones in one pile and all the blue ones in another, with a boundary plain to see; but mixing two rules at once, colour for some and shape for others, makes the groups overlap. Why fix a rule? Sorting means putting things with the same feature into one group, and without a rule nothing can be grouped. A common mistake is changing the rule halfway, starting with colour and switching to shape, and then nothing fits anywhere.
2. Step 2: Place one by oneAfter choosing the rule, pick up one thing at a time and ask: which group does its colour or shape belong to? Then put it there, handling one thing at a time. Example: the red ball goes into the red group and the blue ball into the blue group; with 8 toys on the desk, pick each one up, look, think, and place it, and when all are done the sorting is complete. Why one at a time? Taking several at once easily puts things in the wrong group or leaves one out. A common mistake is rushing and dropping several together, so a clearly blue ball stays in the red group.
3. Step 3: Count each groupAfter sorting, count how many things are in each group and write the numbers down. Example: 5 things in the red group and 3 in the blue group, written as 'red 5, blue 3', and anyone can read the result at a glance. Sorting plus counting is really doing statistics, and every row of a picture graph comes from counting groups exactly like this. Why record? Only when the numbers are written down can we compare them and answer which group has the most. A common mistake is counting and walking away without writing, then forgetting and counting all over again.
4. Step 4: Sort again by another featureThe same things can be sorted again by a different feature, and the result will change. Example: the same box of blocks was sorted by colour just now; sort it by shape and the squares go in one pile and the circles in another, where before the piles were red and blue. Why is the result different? A different feature means a different sameness, so the grouping follows, and that is exactly the fun of sorting. A common mistake is changing the feature but keeping the old groups and counting the new feature along them; every time the rule changes, start again from the first step.
5. Step 5: Check for mistakesAfter sorting, check every group: is the feature of everything inside the same? Was anything put in the wrong group? Example: if a blue ball is found in the red group, move it to the blue group, and look over the desk to see whether anything still belongs to no group. The checking rule is 'same inside a group, different between groups'. Why check? One misplaced thing makes the counted numbers wrong, and the statistics after them go wrong too. A common mistake is counting the moment sorting ends and skipping the check; spend one minute verifying first, and the result is reliable.
6. Step 6: Sorting in lifeSorting is useful everywhere in life, and what is learned in the lesson can be used at home. Example: when packing your school bag, books go in one layer and stationery in one pocket; when tidying the toy box, cars go in one box and blocks in another; in the wardrobe, socks and shirts each have their own place. All of these are the same process: choose a rule, place things one by one, then check. Why sort? Sorted things are easy to find, and rooms and school bags stay tidy. A common mistake is putting things anywhere, then searching for ages next time; a few minutes of sorting every day keeps everything in order.

4Diagrams Diagrams

5Worked example Example

6Common mistakes Mistakes

7Quick check Quick check

8Recap Recap

• Sort: put similar things together by one feature.
• One feature at a time: colour, shape or size.
• After sorting, count each group and add up to check.
• The same things can be sorted another way.
• Sorting is the first step of statistics.