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The Lumenary
幼儿园至二年级Geometry & Topology计划中

Measuring length and time

Comparing and ordering objects by length, measuring with non-standard and standard units, and telling time to the hour and half hour.

math.geom.measurement

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前置知识

Counting

2 项必需的前置知识（一直追溯到底）

你将学会

  • Compare and order objects by length, directly and by using a third object.
  • Measure lengths by laying copies of a unit end to end without gaps or overlaps, and then with a ruler.
  • Tell and write time to the hour and half hour on analogue and digital clocks.

定义

  • A unit is a fixed amount used for measuring, such as a centimetre or the length of a paper clip.
  • The length of an object is the number of units that fit along it end to end.

定理

  • Measuring the same length with a smaller unit gives a larger number.
  • If A is longer than B and B is longer than C, then A is longer than C.

常见误解

  • Starting to measure from 1 on a ruler instead of from 0.
  • Leaving gaps or overlaps between units.
  • Thinking a string becomes shorter when it is bent.

通向

Area, perimeter and angles

可选发现