Estimating Lengths

PROCEDURAL

Mathematics›Measurement|Ages 7—8|ID: mt_OzRZ89GrQW

Estimate lengths using units of inches, feet, centimetres, and metres

Mastery Evidence

Estimate the length of a classroom object before measuring it
Use a known reference (e.g. width of a finger ≈ 1 cm) to make reasonable estimates
Check estimates by measuring and evaluate how close they were

Assessment Prompt

“If [child] looks at a car parked outside, can they estimate roughly how many metres long it is — and then check whether their guess was reasonable?”

Curriculum Standards1 alignment

2.MD.3Common Core State Standards for Mathematics

Estimate lengths

Estimate lengths using units of inches, feet, centimeters, and meters.

Measurement and Data

Prerequisites1

Measuring length (age 7+)
hardAges 7—8

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Measuring length (age 7+) hard
Estimating lengths requires experience with standard units from measuring
- Measuring length (age 6+) hard
  Using standard measurement tools extends measuring with non-standard units
  - Measuring length and height (age 5+) hard
    Measuring with iterated units extends Y1 beginning to measure length
    - Comparing Lengths & Heights hard
      Measuring length with units requires first being able to compare lengths directly
      - Measurable Attributes of Objects hard
        Comparing lengths/heights requires first identifying length as a measurable attribute
  - Measuring length soft
    Measuring with units benefits from ability to order and compare lengths
    - Comparing Lengths & Heights hard
      Ordering 3 objects by length and indirect comparison extends direct length comparison
      - Measurable Attributes of Objects hard
        Comparing lengths/heights requires first identifying length as a measurable attribute
- Choosing measurement units soft
  Choosing appropriate tools builds on choosing appropriate units
  - Capacity and volume hard
    Using standard units for capacity extends from beginning to measure capacity
    - Comparing Capacity hard
      Measuring capacity with units requires first being able to compare capacities
      - Measurable Attributes of Objects hard
        Comparing capacity requires understanding capacity as a measurable attribute
  - Measuring length and height (age 5+) hard
    Using standard units for length extends from beginning to measure length
    - Comparing Lengths & Heights hard
      Measuring length with units requires first being able to compare lengths directly
      - Measurable Attributes of Objects hard
        Comparing lengths/heights requires first identifying length as a measurable attribute
  - Measuring mass and weight hard
    Using standard units for mass extends from beginning to measure mass
    - Measuring mass and weight (age 4+) hard
      Measuring mass with units requires first being able to compare masses directly
      - Measurable Attributes of Objects hard
        Comparing mass/weight requires first identifying mass as a measurable attribute

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