I use a 1/4" foot bought for my Bernina 125. On my Featherweights, rather than using a special 1/4" foot, I simply use the left, longer toe of the standard FW foot. This also works on Vintage Singer machines. If a student brings his/her own machine without the foot, I suggest either painters' tape (which doesn't leave a residue on the machine surface) or a thin stack of Sticky Notes (also residue-free.)
If I'm looking for a 'scant' quarter inch seam, I am able on the Bernina to move my needle one position to the left or right, depending on how I'm stitching.