In the workshops I teach to elementary-age animators, we work exclusively on paper, without student workstations. We emphasize self expression and immediacy over skill, and there really isn’t time to teach 9-mouth-shape lip sync of the classical Disney variety. Instead, we use a haphazard, 2-shape method I like to call “mouth flapping”.
The closed-mouth/resting position [L] is drawn onto the character itself. The open-mouth position [R] is achieved by cutting an oval out of a separate piece of paper that is the same color as the closed mouth, and at least as wide (if not slightly wider), then placing the replacement mouth on top of the drawing of the closed mouth temporarily.
If you have Dragonframe, you can import your dialogue and add the open-mouth overlay for frames corresponding to the peaks of your waveform, and that’s really all there is to it. If you don’t have Dragonframe, you can switch between the two mouth shapes haphazardly — say every 4 or 6 frames if working at 12fps — and honestly most people (probably any non-animator) won’t even notice or cave that it’s not quite in sync.