Grade 5 · Design & Engineering · Lesson 139

Cardboard Grabber

Build a safe cardboard grabber that picks up and moves three large paper balls without using fingers on the balls.

Time2 × 45 minutesTeamsPairs; alternate builder and testerEquipmentBasic classroom design materials; no powered equipment

Your project in view

What you are making

Build a safe cardboard grabber that picks up and moves three large paper balls without using fingers on the balls.

This generated example illustrates one possible finished design—not actual student work. Use the lesson’s sizes, connected parts and safety steps; your colors and creative details can be different.

Generated finished-project example for Cardboard Grabber: Build a safe cardboard grabber that picks up and moves three large paper balls without using fingers on the balls.
Cardboard Grabber · Generated project example

Student directions · Grade 5

What will you make and do?

Build a safe cardboard grabber that picks up and moves three large paper balls without using fingers on the balls.

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

    Measure a paper ball. Draw two jaw shapes and mark the handles, pivot points and opening direction.

  2. 2Make the first parts

    Layer cardboard for two broad handles. Adult prepares fastener holes at the marked pivots.

  3. 3Put it together

    Join the handles and add soft, broad cardboard jaws. Cover rough edges and test the motion without a load.

  4. 4Test it fairly

    Move three paper balls between bowls in three rounds. Record drops, crushed balls and loose joints.

  5. 5Improve one part

    Change one jaw angle, grip surface or pivot position. Repeat with the same balls and bowl spacing.

  6. 6Show and turn in

    Submit the grabber, motion diagram and transfer results. Demonstrate how the pivots move the jaws.

How will you know it works?

  • Moves all three paper balls without direct finger contact
  • Jaws and pivots remain attached through three rounds
  • Record the stated test and explain one revision

Before you move on

Explain which measurement, input or design choice you are testing. Predict the result and record what stays the same so your comparison is fair.

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

Define the need in Build a safe cardboard grabber that picks up and moves three large paper balls without using fingers on the balls. Agree on the two success checks and the listed material limits.

What students show: Two labeled ideas with the target and limits stated.
Practiced

3-5-ETS1-2

Compare the ideas using the project checks: Moves all three paper balls without direct finger contact; Jaws and pivots remain attached through three rounds.

What students show: A selected design with a reason connected to a success check.
Assessed

3-5-ETS1-3

Test, change one feature and retest: Move three paper balls between bowls in three rounds. Record drops, crushed balls and loose joints. Change one jaw angle, grip surface or pivot position. Repeat with the same balls and bowl spacing.

What students show: Before-and-after results collected under the same conditions.

Materials

  • Cardboard strips
  • paper fasteners
  • tape
  • three large paper balls
  • two bowls
  • ruler
  • Pencil, planning paper and the printable design brief below

Teacher preparation

  1. Gather per-pair materials: Cardboard strips; paper fasteners; tape; three large paper balls; two bowls; ruler.
  2. Make one rough sample and rehearse the exact test: Move three paper balls between bowls in three rounds. Record drops, crushed balls and loose joints.
  3. Set the size, load or distance marks mentioned in the steps before class. Demonstrate an ordinary first attempt, not a perfect model to copy.
  4. Prepare any holes, fasteners or difficult cuts for students. Check the stated safety note and clear the testing space.

Step by step

How to teach it

Meeting 1 · 0–8 min

See the job and plan

  1. Introduce the finished object: Build a safe cardboard grabber that picks up and moves three large paper balls without using fingers on the balls.
  2. Measure a paper ball. Draw two jaw shapes and mark the handles, pivot points and opening direction.
  3. Students say what would count as a successful result.
Meeting 1 · 8–18 min

Model the unfamiliar action

  1. Demonstrate slowly: Layer cardboard for two broad handles. Adult prepares fastener holes at the marked pivots.
  2. Pause so partners can repeat the action; provide prepared parts if cutting or folding blocks progress.
Meeting 1 · 18–35 min

Build the first version

  1. Join the handles and add soft, broad cardboard jaws. Cover rough edges and test the motion without a load.
  2. Partners swap builder and checker roles halfway through. Check the working part before decorating.
Meeting 1 · 35–45 min

Try once and save

  1. Run one trial of the stated test to locate an obvious problem. Do not count a changed procedure as a fair comparison.
  2. Label and store the model; sketch its current shape and clear the work area.
Meeting 2 · 0–8 min

Predict and set up

  1. Revisit the two success checks. Agree on identical starting conditions and prepare a before/after results table.
Meeting 2 · 8–23 min

Collect evidence

  1. Move three paper balls between bowls in three rounds. Record drops, crushed balls and loose joints.
  2. One student operates while the other records. Swap for a later trial while noting a change of operator if it affects the result.
Meeting 2 · 23–35 min

Change one thing

  1. Change one jaw angle, grip surface or pivot position. Repeat with the same balls and bowl spacing.
  2. Keep the original results rather than replacing them with only the best attempt.
Meeting 2 · 35–45 min

Explain and clean up

  1. Submit the grabber, motion diagram and transfer results. Demonstrate how the pivots move the jaws.
  2. Collect the brief and results; separate reusable materials and clean the test area.

Assessment

  • Moves all three paper balls without direct finger contact
  • Jaws and pivots remain attached through three rounds
  • Student demonstrates the actual task: Move three paper balls between bowls in three rounds. Record drops, crushed balls and loose joints.
  • Record includes failures as well as successes.
  • Student identifies one changed feature and uses the retest to explain the result.

Supports & extensions

  • Provide a worked first joint or sample; have students record dimensions and explain one comparison limitation.
  • Start with the smallest working version of cardboard grabber before decoration.
  • Extension after success: choose one more value for the same tested feature, predict its effect and repeat move three paper balls between bowls in three rounds.

Safety & responsible use

  • Teacher checks materials and test conditions before use. Use classroom scissors; adults prepare difficult cuts, holes and fasteners.
  • No powered tools, coding, hot glue or electrical circuits are required. Keep moving objects contained and test loads light.
  • Adults prepare holes and difficult cuts. Use only soft, large objects; never point, pinch, or test the grabber on a person.

No-machine alternative

Use prepared paper parts, larger pieces or an adult-assisted version of the same build. Keep the functional task: Build a safe cardboard grabber that picks up and moves three large paper balls without using fingers on the balls. If physical testing is not possible, label sketches as predictions rather than measured results.

Printable student design brief

The challenge

Build a safe cardboard grabber that picks up and moves three large paper balls without using fingers on the balls.

Success criteria

  • Moves all three paper balls without direct finger contact
  • Jaws and pivots remain attached through three rounds
  • Record the stated test and explain one revision

Constraints

  • Use only the listed teacher-approved materials
  • Stay within the teacher-set size, load and test-space limits
  • Two 45-minute meetings; keep the first version simple

Engineer’s notes

Who uses this object, and what should it do?
Draw two possible designs. Label the working parts and circle your choice.
Which size, fold, gap or position must you measure or mark?
Before testing, predict what will happen: Move three paper balls between bowls in three rounds. Record drops, crushed balls and loose joints.
Record each trial: condition / expected result / actual result.
Draw the ONE change you made. What stayed the same?
Record the retest. Did the change help, not help, or leave the result uncertain?
Show and explain: one result that supports your conclusion.
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