Your own workspace
Seeded with an example project. Yours to break — **Reset** puts it back.
Shipbuilder
Read a page, do it in a real workspace, check your work.
Checked against the database
Each criterion is reported separately, so you know which part is missing.
Checked by you
What the database cannot see, an annotated screenshot shows and you confirm.
Three kinds of exercise
Do something and have it checked; find something and answer for it; or work
through a story that changes under you as you go.