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Potato Contour Drawing: Blind and Modified Edge Studies
Learn potato contour drawing through blind and modified edge studies. Build observation skills with clear steps, a worked example, and four practice tasks.
Free lesson
Four exercises
Worked answers
Object Drawing Lessons
Contour drawing trains your eye to follow an edge slowly while your hand records what it sees. A potato is an ideal subject because its outline is irregular but closed, with bumps, dents, and a stem scar that create varied edge events. This lesson focuses on three related studies: a standard contour drawing, a blind contour where you do not look at the paper, and a modified contour where you glance only to place the pen. You will use a simple convention: x-height means the distance from the baseline to the midline of a lowercase x in your normal handwriting. Letter styles vary, so measure your own x-height rather than assuming a standard. All numerical values below are hypothetical examples for practice, not manufacturing or printer specifications. The goal is not a perfect potato but a record of sustained looking.
Practice materials: Printable downloads are not available for this lesson yet. Use the instructions and four exercises below.
Set Up and Define Your Convention
Choose one potato with a clear silhouette. Place it on a plain surface at eye level. Tape your paper so it cannot shift. Draw a light baseline and midline on the paper using your own x-height as the unit: for example, if your x-height is 4 mm, make the baseline-to-midline gap 4 mm. This gives you a checkable scale for judging edge length and spacing without claiming any standard.
Use a single pen or pencil. For blind contour, cover or turn away from the paper. For modified contour, allow one brief glance per edge segment to place the pen, then return your eyes to the potato. Keep the pen moving at a slow, steady pace. If you lose the edge, stop, relocate the feature on the potato, and continue from where you stopped rather than inventing a line.
- Measure your x-height on scrap paper and record it in millimetres.
- Draw a baseline and a midline separated by that x-height on the drawing paper.
- Place the potato so its widest point is roughly parallel to the baseline.
- Label three panels: blind, modified, and observation redraw.
Blind Contour: Follow Without Looking
Blind contour means your eyes stay on the potato while your hand draws. Start at the stem scar or a prominent bump. Move your eye along the edge at about one x-height per second. Let your pen travel the same distance on paper. Do not lift the pen unless the edge truly breaks. The resulting drawing may be distorted; that is expected and useful because it shows where your attention jumped.
After finishing one full circuit, compare the number of edge events you recorded with the potato. An edge event is any change in direction, such as a bump, dent, or flat section. If you recorded fewer events than you can count on the potato, repeat the blind study on a fresh panel with a slower pace.
- Fix your eyes on the starting feature and do not look at the paper.
- Move the pen continuously for one complete outline circuit.
- Count edge events on the potato and on your drawing.
- Repeat once if your count differs by more than two events.
Modified Contour: Glance to Place, Then Look Back
Modified contour allows short glances at the paper to place the pen at the start of each segment. Look at the potato for most of the segment, glance only to confirm the pen position, then return your eyes to the potato. Keep segments short: about two to three x-heights of edge per glance. This reduces the wild displacement of blind contour while preserving sustained observation.
Use the baseline and midline as reference marks. For example, if the potato's widest bump sits one x-height above the baseline, check that your drawn bump is also about one x-height above the baseline. These are hypothetical example values; measure your own drawing and potato rather than assuming a fixed scale.
- Draw one short edge segment while watching the potato.
- Glance briefly to place the pen for the next segment.
- Return your eyes to the potato and continue.
- After one circuit, check bump heights against the baseline and midline.
Observation Redraw and Comparison
On the blank panel, redraw the potato from observation without blind or modified rules. Work slowly and compare your three drawings side by side. Ask which edge events were captured in each study and which were missed. A valid drawing may differ in proportion or style; judge it by whether the recorded edge events match the potato's visible features, not by resemblance to a single ideal outline.
Use simple arithmetic to check consistency. If your x-height is 4 mm and you recorded 12 edge events around the outline, the average spacing is about 48 mm divided by 12, or 4 mm per event. This is a hypothetical example. Measure your own values and keep units consistent in millimetres.
- Redraw the potato once from direct observation.
- List three edge events present in all three drawings.
- List one edge event missed in the blind study but captured in the modified study.
- Record your x-height and the number of edge events for each drawing.
Worked example
A student measures an x-height of 5 mm. On the potato they count 10 edge events around the outline. They draw a blind contour and count 7 edge events on the paper. What is the average spacing per event on the potato, and what does the count difference suggest?
Worked answer
Average spacing is not directly computable without the outline length, so use the count comparison. The potato has 10 events and the drawing has 7, a difference of 3. Since the difference exceeds two events, the student should repeat the blind study at a slower pace. If the outline length were hypothetically 50 mm, average spacing would be 50 divided by 10, or 5 mm per event, matching the x-height example.
Four practice exercises
Exercise 1
A potato outline has 8 edge events. A blind contour drawing records 5. The student's x-height is 6 mm. State whether the difference exceeds two events and what the student should do next.
Show answer and check
The difference is 3 events, which exceeds two. The student should repeat the blind study at a slower pace and recount edge events on both the potato and the new drawing.
Why: Subtract 5 from 8 to get 3. Compare 3 with the threshold of two. Since 3 is greater, repeat the study. The x-height of 6 mm is recorded but not needed for this count check.
Check: Recount edge events on the potato and the drawing independently, then subtract the smaller count from the larger.
Exercise 2
A modified contour study uses segments of about two x-heights. If the x-height is 4 mm, what is the approximate segment length in millimetres? Show the arithmetic.
Show answer and check
The approximate segment length is 8 mm, because 2 multiplied by 4 mm equals 8 mm.
Why: The rule states two to three x-heights per glance. Using two x-heights and a measured x-height of 4 mm gives 2 times 4 equals 8 mm. This is a hypothetical example value.
Check: Measure one drawn segment with a ruler and compare it with 8 mm; repeat for three segments and note any variation.
Exercise 3
A student draws a blind contour but looks at the paper twice. They count 9 edge events on the potato and 9 on the drawing. Is the study valid as a blind contour? Explain.
Show answer and check
No. A blind contour requires no looking at the paper during the circuit. The matching count does not make it valid; the student should repeat without looking and recount.
Why: The defining rule is eyes on the potato for the full circuit. Looking twice breaks that rule regardless of the count. The count check is separate from the blind rule.
Check: Ask the student to describe their eye movements during the circuit and confirm no paper glances occurred.
Exercise 4
An observation redraw shows a bump one x-height above the baseline. The potato's same bump is about one and a half x-heights above the baseline. The x-height is 5 mm. Describe the discrepancy in millimetres and one correction step.
Show answer and check
The drawn bump is 5 mm above the baseline, while the potato bump is about 7.5 mm above it, a discrepancy of about 2.5 mm. One correction step is to re-measure the bump height on the potato and adjust the redraw using the baseline and midline.
Why: One x-height is 5 mm and one and a half x-heights is 7.5 mm. Subtract 5 from 7.5 to get 2.5 mm. The correction uses the same baseline and midline reference.
Check: Measure both heights with a ruler in millimetres and subtract the smaller from the larger.
Common mistakes
- Looking at the paper during a blind contour study. Turn the paper away or cover it, and keep your eyes on the potato for the full circuit.
- Drawing too fast and skipping bumps and dents. Slow to about one x-height per second and count edge events aloud as you draw.
- Lifting the pen whenever the line feels wrong. Keep the pen down for one complete circuit; relocate the edge on the potato and continue from the stop point.
- Assuming a fixed x-height instead of measuring your own handwriting. Measure your own lowercase x from baseline to midline and record the value in millimetres.
Self-check rubric
- Blind contour keeps eyes on the potato for one complete circuit without looking at the paper.
- Modified contour uses brief glances only to place the pen, with most time spent observing the potato.
- At least three edge events from the potato appear in the observation redraw.
- X-height is measured and recorded in millimetres, and units stay consistent.
- Comparison notes identify one captured and one missed edge event across studies.
- Valid alternative styles are accepted if edge events and scale checks are documented.
Questions and answers
What counts as an edge event on a potato?
Any visible change in direction along the outline, such as a bump, dent, flat section, or stem scar. Count them on the potato first, then compare with your drawing.
How long should each study take?
A blind circuit often takes two to four minutes at a slow pace. Modified contour may take similar time because of the glances. Use a timer and record your actual duration.
Can I use a different vegetable?
The brief specifies a potato. Use a potato so the edge events and stem scar match the lesson's focus.
Why measure x-height instead of using a ruler grid?
X-height ties the scale to your own handwriting, which varies by person. Measuring it makes the check personal and repeatable without claiming a universal standard.