Grade 3 · Tinkercad · Lesson 46

Interlocking Building Block

Use repeated measurements and planned gaps to make parts connect.

Time2–3 × 60 minutes + adult printingTeamsTeams of 2–3EquipmentTinkercad + Bambu P1S fleet

Project inspiration · 3 images

See, build, and test

Use these images to understand the kind of making, details, and testing involved. They are inspiration—not designs students must copy.

Finished student example for Interlocking Building Block
01Finished project
Close construction and materials view for Interlocking Building Block
02Construction detail
Students testing and recording results for Interlocking Building Block
03Student testing

Student directions · Grade 3

What will you make and do?

You will design an original block that joins with copies of itself in two ways. Five copies should build a stable structure and separate by hand.

Teacher overview: Students will plan the specific object described below, make and test a first version, then use their results to improve it. Read one step together, demonstrate the unfamiliar action, and let students complete that step before moving on.

  1. 1Plan your project

    Sketch two connection ideas using the class’s shared dimensions. Show the matching solid and opening for each; do not copy a commercial brick.

  2. 2Make the first parts

    Try cardboard tabs or clay connection models. Use the teacher’s tolerance samples to choose a gap that permits assembly without force.

  3. 3Put it together

    Model the solid and matching holes in Tinkercad, using Align and Duplicate. Print a small joint sample before the teacher prints the shared block set.

  4. 4Test it fairly

    Connect five blocks in two arrangements, then separate them by hand. Record stability, sticking and loose connections.

  5. 5Improve one part

    Change one joint dimension and test the same arrangements again. Keep the shared connection sizes documented.

  6. 6Show and turn in

    Show both structures and hand in a joint sketch, chosen fit gap and connection-test record.

How will you know it works?

  • Connects in two ways
  • Five pieces form a stable structure
  • Pieces separate without tools

Before you move on

Tell a partner what you are making. Point to the part you will work on next. Draw or dictate your test notes if writing slows you down.

Machine cutting, printer setup and electrical power-on require adult approval. A basic-materials model is a valid way to demonstrate the design when equipment is unavailable.

Keep your plan, test notes and before-and-after evidence with the printable design brief below. Use the detailed teacher plan and any coding guide for tool instructions. These steps continue across the lesson’s meetings, not all in one sitting.

For teachers

Engineering standards

This shows how the lesson connects to the national NGSS engineering standards and what student work you can collect.

Assessed

3-5-ETS1-1

Teams define the user or purpose and set measurable size, performance, material, and print-time limits before modeling.

What students show: Problem statement, criteria, constraints, measurements, and labeled sketch.
Practiced

3-5-ETS1-2

Students sketch and compare at least two possible forms before choosing or combining features for the digital model.

What students show: Two ideas and a criteria-based design choice.
Assessed

3-5-ETS1-3

Teams use a repeatable test—connect five copies, build the same small tower, gently shake the base, and separate the pieces by hand—identify a failure point, revise one dimension or feature, and retest.

What students show: Test data, version comparison, and evidence-based explanation.

Materials

  • Cardboard tab-and-slot prototypes
  • Teacher tolerance sample set
  • Rulers and connection-test cards
  • Rulers or calipers
  • Graph paper, pencils, cardboard, clay, and tape for prototypes
  • Computer or tablet with educator-managed Tinkercad access
  • PLA filament; teacher sets a project-specific gram and print-time budget
  • Finished test objects appropriate to the lesson

Teacher preparation

  1. Create an educator-managed Tinkercad class and assignment link; students do not enter personal information.
  2. Prepare one navigation demonstration using drag, zoom, orbit, undo, and view cube.
  3. Set the build envelope, minimum wall thickness, minimum feature size, and maximum print time for the class.
  4. Create the file rule G3_46_Team##_v1.
  5. Prepare shared build plates and an adult review queue for dimensions, orientation, stability, material use, and safe slicing.

Step by step

How to teach it

Day 1 · 0–20

Define and measure

  1. Introduce the mission: Invent a building block that connects to copies of itself in at least two ways.
  2. Identify the user, criteria, constraints, and measurements that matter.
  3. Sketch two different solutions at approximately full size.
Day 1 · 20–60

Prototype and compare

  1. Build quick cardboard or clay versions.
  2. Compare both ideas against the shared criteria.
  3. Select or combine features and predict the likely failure point.
Day 2 · 0–15

Tinkercad skill warm-up

  1. Start with a measured base shape.
  2. Duplicate matching connector and receiver features.
  3. Use align and a teacher-provided tolerance gap before grouping.
Day 2 · 15–60

Build the digital model

  1. Place the ruler and enter important dimensions instead of guessing.
  2. Use align and group to create clean, intentional geometry.
  3. Inspect from top, front, side, and underneath; name the file correctly and submit for teacher review.
Day 3

Print, test, and improve

  1. An adult slices, approves, operates printers, and removes parts.
  2. Use the same test procedure each time: connect five copies, build the same small tower, gently shake the base, and separate the pieces by hand.
  3. Revise one dimension or feature in a new Tinkercad version and explain the expected improvement.

Assessment

  • Problem includes a user or purpose plus measurable criteria and constraints.
  • Two sketches show meaningfully different solutions.
  • Tinkercad model uses entered dimensions and purposeful tool choices.
  • Model meets the teacher's printability and material-budget checklist.
  • Test is repeatable and the revision responds to evidence.

Supports & extensions

  • Provide a Tinkercad picture guide and a starter file containing only basic reference shapes.
  • Use mouse practice, larger grid snap, and one new tool at a time.
  • Allow a student to direct a partner or teacher who performs fine cursor movements.
  • Offer measured template objects while preserving choices about form and features.
  • Extension: reduce material, add a moving fit, or create two size variants using parameters recorded on paper.

Safety & responsible use

  • Students do not touch hot ends, heated beds, or moving printer parts.
  • An adult handles slicing approval, printer setup, monitoring, part removal, and support cleanup.
  • Use only lab-approved PLA and teacher-managed accounts; never publish student names or designs publicly without permission.
  • Check finished parts for sharp strings, weak points, and small-piece hazards before use.
  • Printed parts are prototypes—not food-safe, medical, climbing, load-bearing, or life-safety products.

No-machine alternative

Build the final version with cardboard, clay, foam, paper tubes, reusable construction pieces, or teacher-prepared shapes. Keep the same measurements, criteria, fair test, evidence, and revision cycle.

Printable student design brief

The challenge

Invent a building block that connects to copies of itself in at least two ways.

Success criteria

  • Connects in two ways
  • Five pieces form a stable structure
  • Pieces separate without tools

Constraints

  • Uses the shared test dimensions and tolerance options
  • No copied commercial brick design
  • Fits the shared-print material budget

Engineer’s notes

Our user needs…
The measurements that matter are…
Idea A and Idea B are different because…
In Tinkercad we used…
Our test showed…
We changed… because…
Our next version would…
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