A magnetic-crane physics game where students grab junk from the dumpster and stack it as high as they can before it topples. Real gravity, real balance, real problem-solving.
Students operate a real gantry crane with an electromagnet. Every piece of junk is a physics object with its own weight, shape, and bounciness — so towers wobble, lean, and fall exactly like real ones. Success comes from planning, balancing, and learning from each collapse.
There is no "winning screen." The goal is simply to build higher than last time (and higher than the class leaderboard). That open-endedness is the point: children experiment, fail safely, adjust, and try again — the heart of the engineering-design cycle.
Scrap Stack lives at the meeting point of physical science, engineering design, and computational thinking. Below are standards this game genuinely supports — each paired with the specific in-game action that addresses it. Codes and titles are quoted from the CSTA K–12 CS Standards (2017) and the Next Generation Science Standards (NGSS), which Connecticut adopted as its official state science standards in 2015 — so the science codes below are the Connecticut Science Standards.
| Code | Standard | How Scrap Stack addresses it |
|---|---|---|
| 1A-AP-08 | Model daily processes by creating and following algorithms (sets of step-by-step instructions) to complete tasks. | Every placement is a repeatable four-step algorithm: position the crane → lower the cable → grab with the magnet → release at the right moment. Students internalize and refine this sequence. |
| 1A-AP-14 | Debug (identify and fix) errors in an algorithm or program that includes sequences and simple loops. | When a tower wobbles or a piece rolls off, students diagnose why (dropped too high? placed off-center?) and fix their next attempt — hands-on debugging of their own strategy. |
| 1B-AP-08 | Compare and refine multiple algorithms for the same task and determine which is the most appropriate. | There are many ways to reach the same height. Students compare strategies — wide base vs. tall base, using a keyboard as a shelf vs. stacking blocks directly — and settle on what works best. |
| 1B-AP-11 | Decompose (break down) problems into smaller, manageable subproblems to facilitate the program development process. | "Build a 30-foot tower" becomes manageable sub-goals: lay a stable base, add a flat middle layer, then balance the tricky pieces on top. |
| 1B-AP-15 | Test and debug (identify and fix errors) a program or algorithm to ensure it runs as intended. | The whole game is a test-and-refine loop: try a placement, observe the physics result, keep what worked, change what didn't — the essence of iterative testing. |
| Code | Standard | How Scrap Stack addresses it |
|---|---|---|
| 3-PS2-1 | Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object. | A centered piece stays put (balanced forces); an off-center piece tips and falls (unbalanced). Students see this cause-and-effect on every single placement. |
| K-2-ETS1-1 | Ask questions, make observations, and gather information about a situation people want to change to define a simple problem… | "My tower keeps falling at the same spot" — students observe the failure point and define the real problem before their next build. |
| K-2-ETS1-3 | Analyze data from tests of two objects designed to solve the same problem to compare the strengths and weaknesses of how each performs. | Comparing junk types — a flat keyboard vs. a round globe as a base — is a direct test of which "object" performs better for the same goal. |
| 3-5-ETS1-2 | Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem. | With a 3-drop budget and a wobbly tower, students weigh options ("stack the tire now or save it?") against real constraints, then compare outcomes across runs. |
| 3-5-ETS1-3 | Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved. | Switching one variable at a time — same base, different top piece — lets students isolate what makes a tower stronger. Failure points are visible and repeatable. |
Each lesson runs in about 20–30 minutes and needs only devices with a browser. Project your own screen for the demo steps, then let students explore.
Great questions turn play into learning. Ask these while a child shows you their tower — they invite reasoning, not just "I got a high score."
Capstone task — "Design Your Champion Tower": Students plan a stacking strategy on paper (which base, which middle, how to handle the gold piece), build it in their chosen yard, then reflect on what happened versus their plan.
| Skill | 1 · Getting Started | 2 · Building It | 3 · Engineering It |
|---|---|---|---|
| Planning | Builds by trial and error with no stated plan. | Has a rough plan (e.g. "make a wide base") and mostly follows it. | Writes a clear plan naming the base, middle, and how to handle risky pieces — and adjusts it with reasons. |
| Physics & Balance | Places pieces randomly; unsure why towers fall. | Recognizes that centered, low pieces are more stable and uses that sometimes. | Consistently balances load, explains stability using "center of gravity" or "balanced forces," and predicts what will tip. |
| Iteration & Debugging | Repeats the same mistake across attempts. | Notices a failure point and changes one thing next time. | Runs deliberate fair tests, isolates the cause of a collapse, and measurably improves the result. |
| Reflection | Describes the outcome only ("it fell"). | Explains one thing that worked and one that didn't. | Compares plan to result, cites specific evidence (heights, which piece failed), and proposes a next improvement. |