Working with live sketches: what to leave alone and what you can change

Three objects in the sketch are explicitly named (use the to show and hide the labels):

• the point , labeled origin
• the point , labeled unit
• the circle , labeled edge

There is also an explicitly named measurement called the unit length tucked away out of sight at the bottom left corner of the sketch.

Do not change these labels or hide the unit length measurement: if you do, the tools in the Toolbox may not work. If you accidentally change any of these explicit labels or make the sketch otherwise unusable somehow, you can always get a fresh copy of the empty universe by clicking on the .

You can resize the sketch window, and you can also move the disk (drag origin) or resize it (drag unit) to make it fit your window better. However, you should do this before you begin any construction, else points that start life inside the edge may end up outside it or vice versa, and the result may well be chaos!