The general oblique drawing is typically the hardest of the three oblique drawings to draw because of the 3/4 scale at which the depth dimension is projected. If a student is completing this assignment using a manual drawing board and equipment, the 3/4"=1" scale can be found on their engineers scale. A lesson on reading the 3/4" scale will need to be taught prior to this assignment. The students will need to know how to read the 3/4" scale and use it efficiently or this assignment won't be possible for them to complete.
If the students are using a CAD system to draw this assignment they will not need to know how to use the 3/4" scale. It would be beneficial for them to know and I would recommend that they receive the same instructions, however, it isn't essential to completing this assignment. They will, however, need to use some math to figure out the equivalent 3/4 scale measurements.