While some drawing can be done on an ordinary desk, a drawing board is really a better choice. A simple piece of hardwood plywood can be used for student work, and the addition of a quality board cover will make the board perform extremely well.
If the board is to be used with a T-square it will need to have a clean, smooth edge on the left and right sides. A T-square provides a horizontal reference that all lines will be constructed from. The head of the T-square slides on the edge of the board and holds the blade perpendicular to the edge. Be sure to choose a T-square with transparent edges as this makes it much easier to use than the solid kind.
A more expensive but easier to use alternative to a T-square is a parallel straight edge. This tool is permanently installed on a drawing board but serves the same function as the T-square. In the days when professionals drafted by hand a drafting machine was the best choice. Since CAD has replaced manual drafting, these machines are too expensive to justify for student work.