A quick drawing made without rulers or drawing instruments, used to get an idea out of your head and onto paper fast enough to keep thinking.
A freehand sketch is drawn with the pencil alone: no ruler, no set square, no compass.
You sketch to find out what an idea actually looks like, and often the drawing tells you within ten seconds that the idea will not work.
An idea held in your head stays vague, but a sketch on paper has a size, a proportion and a shape you can argue with.
Criterion B, Developing ideas, asks for a range of feasible designs, and a page of twelve quick sketches shows range far better than one careful drawing does.
Keep the rejected sketches in your design folder, because they are the evidence that you explored rather than settled.
Speed Beats Neatness at the Ideas Stage
A sketch that took two minutes costs you nothing to throw away, so you throw it away and try something better.
A sketch that took forty minutes with a ruler feels too expensive to abandon, and you end up defending a weak idea because you are attached to the drawing.
Aim for roughly one sketch a minute when you are generating ideas, ten or twelve thumbnails to an A3 sheet.
Draw fast and loose first, then choose the best two or three and redraw only those at a larger size.
Overlapping, slightly scratchy lines are normal at speed, and designers read them as confident rather than untidy.
Tip
Set a timer for ten minutes and fill a sheet with thumbnails before you allow yourself to judge any of them.
Number every thumbnail so your notes can say "idea 7" instead of describing the drawing again in words.
Turn the page sideways and sketch the same idea from a second angle before moving on.
Construction Lines Do the Hard Work First
Construction lines are faint guide lines that set out position, height and width before any real line goes down.
Draw them with a 2H pencil or with barely any pressure on an HB, so they sit quietly under the finished lines.
They let you fix a mistake by drawing the correct line beside the wrong one, which is faster and cleaner than rubbing out.
A centre line through a symmetrical object stops one half drifting wider than the other, which is the most common freehand error.
Only when the faint lines look right do you press harder and commit to the outline.
Crating Turns a Blob into a Believable Object
Crating means sketching the box the object would fit inside, then carving the object out of that box.
A computer mouse starts as a crate roughly 120 mm long, 60 mm wide and 35 mm high, and the curves are cut off the corners afterwards.
The crate holds the three dimensions in a sensible relationship, so a chunky object does not end up drawn long and flat.
Complicated shapes get several crates: a kettle is a tall cylinder for the body, a thin box for the handle and a wedge for the spout.
The same habit carries straight into isometric and perspective drawing, where the crate is drawn on the proper axes instead of by eye.
Example
To sketch a desk stapler, start with a crate about 150 mm by 40 mm by 55 mm.
Slope the top face down towards the front, then round off the back end where the spring housing sits.
Mark the hinge pin and the rubber foot inside the crate before you add any surface detail.
Line Weight Tells the Eye What Is Solid
Line weight is the thickness and darkness of a line, and varying it is the cheapest way to make a flat sketch look three dimensional.
Use a thick dark line, about 0.7 mm, around the outside where the object meets the background.
Use a medium line where two surfaces of the object meet, such as the fold between the top face and the side.
Use a thin light line for surface detail: a seam, a vent slot, a screw head, a change of colour.
Thicken any edge with nothing behind it, because that is the rule your eye already uses to judge depth in real objects.
A 2B pencil gives you a dark heavy line without pressing hard enough to dent the paper underneath.
Proportion Is What Makes a Sketch Convincing
Proportion is the relationship between the sizes of the parts, and getting it wrong spoils a sketch far faster than shaky lines do.
Pick one part as your unit, say the width of a phone, then judge every other dimension as a multiple of that unit.
Hold your pencil at arm's length against the real object and slide your thumb along it to compare one length with another.
Locate details by halving: find the middle of the whole object, then the middle of each half, rather than guessing a position straight off.
Stand back from the page every minute or so, since proportion errors are obvious at arm's length and invisible with your nose on the paper.
A sketch with true proportion and wobbly lines reads well, while a ruled sketch with wrong proportion just reads as a mistake.
Common Mistake
A sketching page is not a finished product drawing, so do not spend a whole lesson shading one idea.
One beautiful sketch scores poorly for Developing ideas because it shows no range of options.
Rubbing out every stray construction line also removes the evidence of how you built the drawing.
Notes Beside a Sketch Turn It into Evidence
Write beside each thumbnail what the idea is, what material you had in mind and what you are unsure about.
Three words next to a sketch are more use than a paragraph at the bottom of a page holding twelve of them.
Draw a short arrow from the note to the exact part you mean, so nobody has to guess which line you are talking about.
Six weeks later your own sketch is unreadable without those notes, and the teacher marking your ePortfolio never had them in the first place.
Active recall
Why does a two minute sketch make it easier to reject a weak idea than a forty minute one?
What pencil grade and pressure would you use for construction lines, and what are they for?
Describe how you would crate a computer mouse before sketching it.
Which edges of an object get the heaviest line weight, and what does that tell the viewer?
Name two ways of checking proportion by eye while you are still drawing.