The eight tasks
- Midpoint: the exact middle of a line segment.
- One third: one third of the length from the end with the black dot.
- Bisect the angle: the direction that splits the angle into two equal halves.
- Right angle: a line at 90° to the given one. Either side counts, and the nearer one is used.
- Circle center: the point the same distance from every point on the circle.
- Triangle centroid: where the three medians meet, each running from a corner to the middle of the opposite side. Cut out of card, the triangle would balance on a fingertip there.
- Parallelogram: place the fourth corner so that opposite sides are parallel and equal.
- Where lines meet: the point where two lines would cross if they kept going.
How the error is measured
The board is treated as 600 units wide, and your error is the distance between your point and the exact answer in those units. An error of 6 means you were off by 1% of the board's width. Angle tasks are measured along the circle the point moves on, so every task uses the same yardstick. The results show your average and a breakdown by task, so you can see which kinds of judgment come easily and which do not.
Tips
- Long deliberation does not always help. Trust your first impression and refine a little.
- Sit back so you can take in the whole drawing at once.
- Jobs that rely on eyeballing, like woodworking or design, tend to sharpen this skill.