Design and technology
Design log: test and improve a paper bridge
Develop a paper bridge through repeated tests, changing one feature at a time and recording the result. A worked entry models a folded paper deck over a 300 mm gap, followed by spaces for later versions, a decision trail and load comparisons.
This sketch belongs to a made-up bridge test. Read the complete entry for its conditions, result and next step.
Read the complete materialRead the material
Develop a paper bridge through repeated tests, changing one feature at a time and recording the result. A worked entry models a folded paper deck over a 300 mm gap, followed by spaces for later versions, a decision trail and load comparisons.
Complete resource. Use the preview for diagrams and layout.
Page 1
NAME CLASS DATE LEARNING GOAL Improve a design step by step, using test evidence to decide every change. SUCCESS CRITERIA I can change one thing at a time and say why. I can record a test result with a number and unit. I can use my results to plan the next step. BUILD One sheet of A3 paper and 30 cm of tape. GAP TO SPAN between two book stacks TEST Add 10 g masses to the middle, one at a time. RESULT The largest load held for 5 seconds. Read this made-up entry. It logs one change, the reason, a result with a unit and a next step. REV DATE Lesson 2 TEST CARRIED OUT 10 g masses on the middle, 300 mm gap RESULT (NUMBER AND UNIT) Held 310 g; failed at 320 g WHAT I CHANGED AND WHY Folded the deck lengthways into a zigzag with 2 cm folds. Version A was flat: it sagged and held only 120 g. NEXT STEP At 300 g the folds began to spread. For C, tape a strip across each end to hold them. SKETCH OR PHOTO 300 mm 10 g masses end view: zigzag Version A is your first bridge. Test it, log it, then change one thing for B. REV DATE TEST CARRIED OUT RESULT (NUMBER AND UNIT) WHAT I BUILT AND WHY NEXT STEP SKETCH OR PHOTO REV DATE TEST CARRIED OUT RESULT (NUMBER AND UNIT) WHAT I CHANGED AND WHY NEXT STEP SKETCH OR PHOTO Iterative design log STAGE Test SCALE Not to scale Sheet 1 of 3 DESIGN AND TECHNOLOGY AGES 14 TO 16 ITERATIVE DESIGN DESIGN LOG: A PAPER BRIDGE Build, test, change one thing, test again. Log every step as evidence. 1 The challenge and a model entry EXAMPLE 300 mm B EXAMPLE 2 Log versions A and B Your log A B
Page 2
Keep the test the same every time: same gap, same masses, same place on the deck. REV DATE TEST CARRIED OUT RESULT (NUMBER AND UNIT) WHAT I CHANGED AND WHY NEXT STEP SKETCH OR PHOTO REV DATE TEST CARRIED OUT RESULT (NUMBER AND UNIT) WHAT I CHANGED AND WHY NEXT STEP SKETCH OR PHOTO Link your versions. Copy each result, then work out the change in load from the version before. REV MAIN CHANGE FROM THE VERSION BEFORE LOAD HELD CHANGE IN LOAD KEEP IT? EXAMPLE Folded the deck into a zigzag 310 g +190 g (310 − 120) Yes My first bridge (the starting point) g none Yes No g g Yes No g g Yes No g g Yes No BEST VERSION LOAD HELD g THE CHANGE THAT HELPED MOST, AND MY EVIDENCE GO FURTHER How many times stronger is your best version than A? Work out best ÷ A. Example: 310 ÷ 120 = about 2.6. BEST (G) A (G) TIMES STRONGER Iterative design log TESTED BY REV Sheet 2 of 3 DESIGN AND TECHNOLOGY AGES 14 TO 16 ITERATIVE DESIGN KEEP IMPROVING, KEEP THE EVIDENCE 3 Log versions C and D Your log C D 4 Decision trail SUMMARY B A B C D D
A teaching sequence
Improve a design using a controlled test, recorded evidence and a reasoned next step.
Record the starting bridge
Build a starting bridge from agreed materials and record its version and setup. The example uses A3 paper and 30 cm tape over a 300 mm gap.
What gap, materials and version identify this build?
Test and record the load
Add 10 g masses at the centre and record the largest load held for five seconds and where failure occurs.
What load was held for five seconds, and where did failure occur?
Change one design feature
Change one feature in each new version, sketch it and explain why. Keep the gap, masses and load position constant for fair comparison.
Which test conditions stayed fixed while you changed the design?
Compare using the recorded loads
Compare the largest loads held for five seconds under the recorded setups and identify the best-performing version. Use the printed 310 g and 120 g values to calculate a held-load ratio for this test.
What does the ratio of held loads show, within this classroom test?
Before you teach
Look for the thinking behind an answer, choose the support your class needs and leave room for an independent response.
What to look for
Check that the test conditions remain the same, the load and gap use units, and each revision changes one feature. Ask pupils to link their design decision to a measured result and note any limitations such as shifting supports or inconsistent placement.
Give a little support
Use stable supports and small, manageable masses under teacher supervision. Demonstrate how to place a load centrally and stop safely when the structure shifts. Pupils can contribute through sketching, recording, measuring or evaluating.
Take the idea further
Ask pupils to repeat the best design test and discuss whether it produces a similar result. They can compare load held with material use and propose a further change that could be tested without changing multiple variables.
Things to keep in mind
A classroom bridge challenge is not a certified structural test. Loads and supports must be suitable for the work area and pupils. A single test result may reflect build variation, so avoid claiming that one design is universally stronger.
Keep the idea. Make it yours.
Bring your topic, learning goal and class context to PLAI™, then review what you create.
Ideas to try with your class
Sample teaching perspectives on what to try, what to adapt and what to watch for.
Meet The Creators
Meet a creator whose teaching interests connect with this template.
One Last Sticky Note
The paper-bridge log fixes A3 paper, 30 cm tape, a gap and 10 g loads, then records the largest load held for five seconds. Its fictional example compares a flat bridge with a folded zigzag and names one next change.
Coffee Before Copies
The design log follows test, evidence, change and retest. Recording a 310 g result and a failure at 320 g gives pupils a model for precise results and reasoned iteration.
Glue Stick Club
The revision fields ask what changed, why, what happened and what comes next, with a sketch to make the construction visible. Keeping each revision separate can help pupils identify which change may have affected the result.
Bright Idea Break
The worked entry is made up and should not be treated as a guaranteed bridge design. Keep span, loads and test duration consistent between versions if pupils are comparing performance.