Lesson 24 · Unit 4

Sketching as a
Design Tool

Use informal and formal drawing at the right stage to explore, refine and communicate design thinking.

80 minutesA2.2.2Analogue + digital

Guiding question: Why do designers use different drawing techniques at different stages of design?01

Today’s destination

By the end of class, you should be able to…

Compare drawing types

Explain advantages and disadvantages of informal and formal analogue/digital drawing.

Sketch rapidly

Use free-hand and iterative sketches to explore alternatives.

Communicate form

Recognize when isometric or orthographic views are useful.

Annotate reasoning

Use written notes to make design intention and evidence visible.

Success check: explain the concept accurately, then use it to make a justified design decision.

Know it → use it → explain the evidence.02

A2.2.2

Drawings serve different purposes.

A2.2.2 expects designers to choose drawing techniques that fit the stage of design.

Explore

Fast + disposable

Loose free-hand sketches make it cheap to test many possibilities.

Refine

Compare + develop

Iterative sketches show dimensions, mechanisms, user interaction or feature changes.

Communicate

Precise + interpretable

Formal drawings help other people understand geometry, dimensions and assembly.

Use the least expensive representation that answers the current design question.03

A2.2.2

Precision has a cost—and a purpose.

Informal drawing

Fast, flexible, idea-rich.

Advantages: quick, low commitment, supports divergence and annotation.
Disadvantages: may be ambiguous, inconsistent in scale, harder for manufacturing communication.

↔

Formal drawing

Controlled, standardized, precise.

Advantages: clearer geometry, dimensions and interpretation.
Disadvantages: slower; can encourage premature commitment if used too early.

Choose drawing fidelity to match the design stage.04

Medium choice

Both can be informal or formal.

	Analogue	Digital
Strength	Immediate hand–eye exploration; low setup.	Easy editing, duplication, layers, precision and sharing.
Limitation	Harder to revise cleanly or reuse geometry.	Tool learning and software friction can slow early ideation.
Good stage	Rapid sketching, brainstorming, quick overlays.	Refinement, clean presentation, CAD-based communication.

The best medium is the one that helps you think and communicate effectively.05

Explore form quickly

Sketch structure before detail.

Use light construction lines.

Block the main proportion first.

Clarify important edges / interaction areas.

Annotate the feature’s purpose.

A sketch does not need artistic perfection to be useful design evidence.06

Refine visibly

Show what changed and why.

Initial concept

Basic form / mechanism / arrangement.

Evidence-driven change

Increase grip area after user handling feedback.

Refined solution

Adjust angle after reach test and component interference check.

Iteration should communicate a reason for each change.07

3D communication

Isometric drawings help communicate three-dimensional form.

Useful for showing overall form and spatial relationships in one view.

Watch for: perspective-looking distortions. Isometric representation uses consistent axes rather than vanishing points.

We will construct and interpret isometric drawings in Lesson 30.08

2D communication

Orthographic projection separates views for precision.

front view

side view

Multiple aligned views communicate true shapes and dimensions more reliably than a perspective sketch.

Orthographic projection becomes essential when precise manufacture information is needed.09

Apply it

Choose the drawing technique

You have five minutes to explore three alternative handle layouts before asking a user which direction feels most promising.

Which approach is most appropriate first?

Choose before you reveal the feedback.10

Make thinking visible

Move from label → function → evidence.

Level 1

“Handle”

Names the part.

Level 2

“Angled handle improves wrist position.”

Explains design intention.

Level 3

“12° handle angle responds to user discomfort evidence; test with task-completion rating.”

Links feature, evidence and testing.

IB annotations should help another person interpret your design reasoning.11

20-minute activity

Three views of one idea.

One rapid free-hand exploration sketch.

One refined isometric-style sketch.

One simplified orthographic front + side view.

Add at least four annotations that explain reasoning.

Use the same concept so you can compare what each drawing communicates best.12

Vocabulary lab

Drawing vocabulary

Retrieve first. Then check.

TermInformal drawingClick to reveal

MeaningA flexible, often rapid drawing used to explore or communicate developing ideas without full formal conventions.

TermFormal drawingClick to reveal

MeaningA controlled drawing that uses conventions, precision and/or standard presentation to communicate geometry clearly.

TermFree-hand sketchClick to reveal

MeaningA quickly drawn representation created without mechanical construction tools.

TermIterative sketchClick to reveal

MeaningA drawing that develops or modifies an idea across versions based on reasoning, evidence or feedback.

TermIsometric drawingClick to reveal

MeaningA 3D representation using consistent axes to communicate form and spatial relationships.

TermOrthographic projectionClick to reveal

MeaningA set of 2D views that communicate an object’s true shapes and dimensions from different directions.

TermAnnotationClick to reveal

MeaningWritten information that explains design features, decisions, evidence or development.

TermDrawing fidelityClick to reveal

MeaningThe degree of precision, realism and detail in a representation.

Say the meaning before you flip the card.13

Knowledge check

Can you retrieve it without looking back?

1. Why can formal drawings be a disadvantage very early in ideation?

They take more time and can encourage premature commitment to one idea.

2. Name four drawing techniques referenced by A2.2.2.

Free-hand sketching, iterative sketches, isometric perspectives and orthographic perspectives.

3. Can digital drawing be informal?

Yes. Digital and analogue tools can both be used informally or formally.

4. What makes an annotation stronger than a label?

It explains why the feature exists and ideally connects it to user evidence, specifications or testing.

Say the answer first. Then reveal it.14

Exit ticket

Before you leave…

1. Name one advantage of informal drawing.

2. Name one advantage of formal drawing.

3. Explain which drawing type you will use first for your IA ideas and why.

Next lesson

IA Day 7 — Finish Criterion B + Begin Ideation

Keep the evidence chain moving: user → research → decision → test.

Curriculum alignment
A2.2.2 informal/formal analogue/digital drawing · free-hand and iterative sketches · isometric and orthographic perspectives.

Lesson complete15 slides

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IB Design Technology SL · Lesson 2415

Sketching as aDesign Tool