Length (1): Comparing Length

1Summary 重點摘要

Learn which is longer or shorter, use direct and indirect comparison.

2Vocabulary cards Vocabulary

3Step by step Steps

1. Step 1: Direct comparisonThe most direct way to compare the lengths of two objects is to put them together: line up one end and see which one reaches further at the other end. Lining up one end matters; without it, no fair comparison can be made. Lay them flat side by side, not one high and one low.
2. Step 2: Which is longerAfter lining up, look at the far ends: the one reaching further is longer, and the one falling short is shorter. Say the result after judging, for example the pencil is longer than the eraser, and the eraser is shorter than the pencil. With more practice you can tell at a glance.
3. Step 3: Indirect comparisonWhen two objects cannot be placed together, compare indirectly: measure one with a piece of string, then move the string to the other to compare, or measure both with a ruler and compare the numbers. The string must be pulled straight for an accurate result. The heights of a door and a window can be compared this way too.
4. Step 4: Everyday examplesComparing lengths is used everywhere in life: a pencil is longer than an eraser, a door is taller than a chair, long trousers are longer than shorts. We compare when buying clothes or lining up, so learning it well is useful. Find a few more examples yourself; the more you find, the more familiar it becomes.
5. Step 5: Speak comparisonAfter comparing, learn to express it in a full sentence: A is longer than B, or B is shorter than A. Name both objects clearly when speaking, for example 'the pencil is longer than the eraser', so the listener understands. Saying only 'long' or 'short' leaves others not knowing what you mean.
6. Step 6: Sort from long to shortSeveral objects can be ordered from longest to shortest: find the longest first, then the longest of the rest, and continue in order. With the order set, the length relationships are clear at a glance; this is also a way of organising information. Check as you order to be sure nothing is misplaced.

4Diagrams Diagrams

5Worked example Example

6Common mistakes Mistakes

7Quick check Quick check

8Recap Recap

• Longer extends further, shorter is shorter
• Direct comparison must align one end
• A is longer than B, B is shorter than A
• Everyday everywhere has length comparison
• Can sort several things from long to short