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Sketch Warm-Ups

Fifteen quick prompts for the start of any design session. Pick one or two, run a 5-minute timer, then move into the day's work.

How to use this page. At the start of a design session, pick one prompt and give students 5 minutes. The point isn't to produce good sketches — it's to warm up the sketching muscle before the real work. Pair this with the printable templates (linked below) where helpful.

The "watch for" notes tell mentors what student behavior signals progress versus stuckness on each prompt. Use them to spot students who need a different intervention from the diagnosis page.

One firm rule: warm-ups are not graded. Don't put them in the engineering notebook. Their job is to lower the activation energy for the real sketching that comes after.

▸ PRINT FOR DESIGN SESSIONS

Print these in advance. ~30 copies of A for any brainstorming session, ~5 copies each of B and C for focused work. They're meant to be consumed — students should leave the session with worked-on paper, not pristine sheets.

▾ FORM GENERATION (3 prompts)

#1 5 min → Template A

Three ways to grab a cup. Don't worry which is best — just three different mechanisms. Claw, pincer, suction, scoop, magnet — pick three and sketch one in each frame.

Watch for: students who draw three nearly-identical claws are not generating real options. Push them: "What if you couldn't use a claw at all?" If they still produce variations on a single concept, that's failure mode 5 (no clear purpose) — they're treating the prompt as decoration, not design.
#2 5 min → Template A

Sketch four different shapes a chassis could be. Give each one a name. Examples: tank, hourglass, H-frame, T-frame, X-frame.

Watch for: students who can't name their shapes likely don't have a vocabulary for what they're drawing — that's failure mode 4 (no vocabulary). Have them touch a real chassis or look at examples on the public mechanism pages before re-attempting.
#3 5 min → Template A

Draw a robot's silhouette from the front in three different design philosophies: tall-and-narrow, wide-and-short, balanced. No mechanisms — just outline.

Watch for: students drawing inside the 18″ envelope correctly. If their "tall-and-narrow" exceeds the envelope, they don't yet have spatial intuition for VEX dimensions — pair with Template B or C next session to internalize scale.

▾ SCALE CALIBRATION (2 prompts)

#4 5 min → Template A

Sketch a 4-inch wheel and a 15-inch chassis next to each other. No measuring while drawing — just by eye. After you're done, check with a ruler.

Watch for: the wheel is almost always drawn too big relative to the chassis. This is a useful diagnostic — students who get the proportions wrong here will get them wrong in real concept sketches too. Worth showing them the actual hardware side-by-side after the warm-up.
#5 5 min → Template A

Draw an Override pin (6.5″ tall, 3.16″ wide at the widest, 1.40″ at the narrowest) at scale next to your hand — for size reference. Hand traced from actual hand.

Watch for: this builds tactile intuition for game element size, which most students under-estimate. After the warm-up, hand them an actual pin if available — the visceral "oh, it's THAT big" moment is the point.

▾ MECHANISM KINEMATICS (4 prompts)

#6 5 min → Template B

Sketch a four-bar at three different angles: 30°, 55°, 80°. Same arm lengths, different angles. Show what the output platform does at each.

Watch for: students drawing the output platform tilting as the arms rotate. That's wrong — it's a parallel-linkage four-bar; the platform stays parallel to the chassis throughout. Students who draw it wrong have the wrong mental model — failure mode 4. Send them to the mechanism page and a hands-on prototype.
#7 5 min → Template B

Draw a chain bar at five positions across its sweep — fully back, halfway back, vertical, halfway forward, fully forward. Show how the pincer stays level at all five positions.

Watch for: students who draw the pincer rotating with the arm haven't internalized the chain-bar level-keeping mechanism. The chain (passive 1:1) is what keeps the pincer level — point them to the chain-bar mechanism page.
#8 5 min → Template C (top view only)

Sketch a six-wheel drivetrain in top view. Show the wheel offset (drop-center) — exaggerate it so it's clearly visible.

Watch for: students drawing all six wheels in a straight line are missing the drop-center concept entirely. The middle wheels sit lower (1/16″ drop typical) so the robot pivots on a shorter wheelbase for turning. If the concept is missing, do the read → build → sketch sequence on the wheel-placement-guide.
#9 5 min → Template B

Sketch a lift mechanism extending upward through three frames. Show what's hidden behind the chassis at each frame — use dashed lines for hidden features.

Watch for: hidden-line convention adoption. This is a technical drawing convention students often haven't been taught (failure mode 3). If they don't use dashed lines naturally, teach them this one convention right after the warm-up — it's the highest-leverage drawing skill they can pick up in five minutes.

▾ COMPARATIVE ANALYSIS (3 prompts)

#10 5 min → Template A

Two ways to mount a motor on a tower: outside the chassis vs inside. Sketch both. List one pro and one con of each below the sketch.

Watch for: students who can't name pros/cons haven't thought about the engineering trade-offs. The right answer set: outside = better cooling/access but eats envelope; inside = compact but harder to wire/service. If they can't articulate this, a discussion is more valuable than another sketch.
#11 5 min → Template A

Compare a four-bar lift to a scissor lift. Sketch both at the same final height. What's different about how they get there?

Watch for: students drawing scissor lifts as four-bars in disguise. Scissor lifts have crossing X-pairs; four-bars have parallel arms. If the geometric distinction isn't clear, this is mode 4 (no vocabulary) — point them at the mechanism-lifts page.
#12 5 min → Template A

Sketch how a robot grabs a cup three ways: claw, pincer, suction. Don't pick the winner — show the trade-offs.

Watch for: students who insist on "the best one" are missing the point of comparative analysis. Reframe: every approach has a context where it wins. Suction is best for smooth surfaces; pincer is best for varied geometry; claw is best for repeatability. The trade-off discussion is the deliverable, not a winner declaration.

▾ CONSTRAINT-DRIVEN (3 prompts)

#13 5 min → Template B

The goal is at H=12″ and the loader is at H=4″. Sketch a single mechanism that reaches both. Show the path the pincer takes from one to the other.

Watch for: students who don't reach both points. This is a real reach geometry problem — Heron's whole architecture exists to solve it. If a student insists on a fixed-arm mechanism, ask "where does the chain bar pivot? What's its arm length? Does it hit the ceiling during transit?" These are the right design questions.
#14 5 min → Template B

Robot must be 18″ or smaller at start, but can extend during match. Sketch a robot that goes from compact-to-extended in two states. Show both states overlaid.

Watch for: students drawing only one state. The point is the transition. Compact stowed pose and extended deployed pose should be DIFFERENT shapes. If they look the same, the deployment isn't doing anything for them and they should reconsider.
#15 5 min → Template A

Drivetrain is 55W max. Wheels are 4″ omni. Sketch three different motor-and-gear arrangements that fit the wattage cap. Pick which is fastest.

Watch for: students who can't compute ground speed from motor RPM and gear ratio. Speed = (motor RPM ÷ gear reduction) × wheel circumference. If the math isn't there, point them at the gear-calculator and gear-ratios pages — sketching won't fix the math gap.

▾ RELATED REFERENCES