How Many Blocks Long? — The Measuring Crew

Your child measures real things around the house by laying identical blocks end to end, then counting them and announcing the result — “The book is 7 blocks long!”

  1. Pick your unit. Gather about 20 identical items — same-size building bricks, wooden blocks, or large paper clips. They must all be the same size.
  2. Choose something to measure. Start with something shorter than your row of blocks will reach — a book, a shoe, a cuddly toy lying down.
  3. Lay the blocks. Start exactly at one end. Place blocks in a straight line, each one touching the last — no gaps, no overlaps — until you reach the other end.
  4. Count and say it. Count the blocks and say the whole measurement, number and unit together — “7 blocks long.”
  5. Guess, then measure. For the next object, ask first — “How many blocks do you think the spoon will be?” Measure and compare with the guess.
  6. Compare two measurements. “The book was 7 blocks and the spoon was 5. Which is longer? How do you know?”

Variation: keep a “measuring crew report” — your child draws each object and you write the number of blocks beside it. Or measure height — stack blocks beside a toy to see how many blocks tall it is.

Requirements

  • Space: A table or a clear patch of floor
  • Surface: Flat and hard, so the blocks sit in a straight row without sliding
  • Materials: About 20 identical units (interlocking bricks of one size, wooden cubes, large paper clips, or dominoes) and household objects to measure. Optional paper and pencil for a report
  • Participants: 1 child + 1 adult; a sibling can be the guesser or the recorder
  • Supervision: Light — watch the first few measurements for gaps and overlaps, then step back

Rationale & Objective

Measuring with repeated identical units is the bridge between comparing (this is longer) and true measurement (this is 7 units long). The Head Start ELOF expects children by 60 months to be measuring with a single repeated unit, HighScope devotes a key developmental indicator to the concept of unit (KDI 37), and Common Core spells out the rules a child must eventually own: lay copies of a shorter object end to end, with no gaps or overlaps, and express the length as a number of units (1.MD.A.2). Clements and Sarama call this stage the End-to-End Length Measurer. Research on how children learn to measure (Lehrer, 2003) shows the ideas hidden inside this simple act — units must be identical, must tile the whole length, and must start at the beginning — are not obvious to young children, who will happily leave gaps or mix big and small blocks. Laying out many separate units makes each of those ideas something you can see and fix, and builds the understanding a ruler later takes for granted. Estimating first strengthens number sense and gives every measurement a little suspense.

Progress Indicators

  • Early: lays blocks with gaps, overlaps, or a wandering line; starts or stops short of the object’s ends; counts the blocks but does not connect the number to the object’s length
  • Developing: lines blocks up end to end with reminders; counts accurately and says the number, sometimes without the unit; guesses are wild but enjoyed
  • Proficient: measures independently from end to end with no gaps or overlaps and states the measurement with number and unit; uses two measurements to say which object is longer
  • Advanced: notices and deals with leftovers (a bit more than 6 blocks); makes sensible estimates before measuring; explains why all the blocks must be the same size

Safety Notes

  • Small bricks, paper clips, and similar units are choking hazards for children under 3 — keep them away from younger siblings and collect every piece afterwards
  • Bricks left on the floor hurt bare feet and can cause slips — measure on a table or tidy up straight away
  • Keep it light if your child’s count does not match yours — recount together rather than correcting, as early measuring is meant to be approximate

Hints

  • Playfulness: your child is the head of the Measuring Crew with a clipboard, and a soft toy has ordered a new bed, so everything about them must be measured
  • Sustain interest: change the unit each time — paper clips, dry pasta tubes, toy cars bumper to bumper, crayons — and measure something new, such as the cat’s tail (if the cat agrees)
  • Common mistake: letting gaps and overlaps slide, or mixing block sizes. Make a deliberately gappy row yourself and ask is that fair measuring? so your child spots the problem
  • Limited space: with no blocks, tear or cut identical paper strips or use same-size coins, and measure small things such as a pencil or your hand
  • Cross-domain: counting the row practises one-to-one counting (number sense); drawing and labelling the report adds early writing
  • Progression: short objects with large units → longer objects needing more than 10 units → estimate first → compare two measurements → measure one object with two different units and talk about why the numbers differ

Sources

  • Head Start Early Learning Outcomes Framework, Mathematics Development — Goal P-MATH 8 (measures objects using standard and non-standard measurement)
  • Common Core State Standards for Mathematics — K.MD.A.1 (describe measurable attributes) and 1.MD.A.2 (express length as a whole number of length units laid end to end with no gaps or overlaps)
  • HighScope Preschool Curriculum — Mathematics KDI 36 (Measuring) and KDI 37 (Unit — children understand and use the concept of unit)
  • Clements, D.H. & Sarama, J. (2014). Learning and Teaching Early Math — The Learning Trajectories Approach (2nd ed.). Routledge
  • Lehrer, R. (2003). Developing understanding of measurement. In J. Kilpatrick, W.G. Martin & D. Schifter (Eds.), A Research Companion to Principles and Standards for School Mathematics. NCTM
  • Sarama, J., Clements, D.H., Barrett, J.E., et al. (2022). Length measurement in the early years — teaching and learning with learning trajectories. Mathematical Thinking and Learning, 24(4)