Chop the Pattern — Brick Train Carriages

Your child builds a long pattern “train” from interlocking bricks, then chops it into identical carriages to find the little piece that repeats.

  1. Snap together a long train of bricks in a repeating pattern, about four repeats long — for example yellow, green, green, yellow, green, green…
  2. Read the train together. Ask, “Which bit keeps coming back again and again?”
  3. Chop it: your child breaks the train apart into carriages, each one holding one complete repeat (yellow-green-green).
  4. Stack or line up the carriages side by side. “Are they all exactly the same?” If one is different, the chop was in the wrong place — snap it back together and try again.
  5. Count: “How many bricks in one carriage? How many carriages make our train?”
  6. Rebuild the train by joining carriages, then make it longer by building whole new carriages rather than adding one brick at a time.
  7. Your child builds a secret carriage of two to four bricks, copies it several times, and joins the copies into a train for you to chop.

Variation: no bricks? Make the train from a row of colored paper squares or bottle caps and mark the chops by laying pencils or straws between the carriages.

Requirements

  • Space: A table or floor area
  • Surface: Table, tray, or hard floor
  • Materials: Interlocking bricks (Duplo, Lego, or similar) or linking cubes in two or three colors, about 8–10 of each; pencils or straws for the no-brick variation
  • Participants: 1 adult + 1 child
  • Supervision: Moderate — the adult builds the first train and prompts the chopping

Rationale & Objective

Many children extend patterns by reciting them item by item (“yellow, then green, then…”) without ever noticing the chunk that repeats. Identifying that chunk — the unit of repeat — is the pivotal step in pattern understanding. In their study of preschool patterning, Papic, Mulligan and Mitchelmore (2011) found that children given a six-month patterning programme understood the unit of repeat better, and most could extend and explain growing patterns a year later, and Clements and Sarama’s learning trajectory places recognizing the pattern unit as a later level, after extending and duplicating. Physically breaking the train and seeing that every carriage is identical makes the unit concrete, and comparing carriages gives instant, built-in feedback without an adult saying right or wrong. Counting bricks per carriage and carriages per train is also an early taste of equal groups — the idea behind skip counting and, later, multiplication. This directly serves the subdomain goal of identifying and describing the rule in a pattern.

Progress Indicators

  • Early: breaks the train at random places or into single bricks; describes the pattern by naming every brick from start to finish
  • Developing: finds the carriage in an AB train; with longer units, chops in the wrong place but notices that the carriages do not match
  • Proficient: chops AB, AAB, ABB, and ABC trains into correct identical carriages, says the rule (“it goes yellow, green, green”), and extends by adding whole carriages
  • Advanced: builds own trains from a planned carriage, tells how many bricks and carriages there are, and can predict the color of a brick further along (“the next carriage starts with yellow”)

Safety Notes

  • Use large bricks (Duplo-size) if younger siblings are around; small bricks are a choking hazard for under-3s
  • Stiff bricks can pinch or frustrate small fingers — loosen tight joins yourself or use bricks that separate easily
  • Sweep up afterwards; stray bricks on the floor are painful to step on
  • If the child cannot find the carriage, do not push — go back to reading the train aloud in rhythm, pausing after each repeat, and try again another day

Hints

  • Playfulness: each carriage is carrying the same passengers — “Every carriage needs one yellow driver and two green passengers. Did anyone get on the wrong carriage?”
  • Sustain interest: take turns building “mystery trains” for each other, or see how long a train you can make from one carriage design
  • Common mistake: starting with a train that is too short. The child needs to see at least three or four repeats before the unit stands out
  • Limited space: thread a pattern of pasta tubes and beads on a string and mark the units with clothes pegs, or draw the train and circle each carriage
  • Cross-domain: snapping and pulling bricks strengthens hands (fine motor); counting carriages links to number sense and equal groups; explaining the rule builds math talk
  • Progression: AB trains → AAB/ABB → ABC → four-brick carriages (AABB, ABAC) → child plans a carriage first → predicting bricks further down the line

Sources

  • Papic, Mulligan & Mitchelmore (2011), “Assessing the Development of Preschoolers’ Mathematical Patterning,” Journal for Research in Mathematics Education, 42(3)
  • Clements & Sarama, Learning and Teaching Early Math: The Learning Trajectories Approach — patterns and structure trajectory (pattern unit recognizer)
  • Rittle-Johnson, Fyfe, Loehr & Miller (2015), “Beyond Numeracy in Preschool: Adding Patterns to the Equation,” Early Childhood Research Quarterly
  • Wijns, Torbeyns, De Smedt & Verschaffel (2019), “Young Children’s Patterning Competencies and Mathematical Development: A Review” (in Mathematical Learning and Cognition in Early Childhood, Springer)
  • Head Start ELOF — Goal P-MATH 7: child understands simple patterns
  • HighScope Key Developmental Indicator 38: Patterns