A third approach flips the usual order: instead of studying the lines first and waiting for an idea to appear, start by writing down ten varied, interesting titles, and then work out how to fit each box's given lines into a picture matching that title.
Before looking closely at any box, brainstorm a free list of ten short, evocative titles covering different kinds of subjects, for instance an animal in an unusual pose, an everyday object doing something odd, a landscape moment, a portrait expression, a machine at work, and so on, without worrying yet about whether the given lines will fit.
Then go box by box, take one title from the list, and figure out how the specific lines already printed in that box could become part of a scene matching that title, rotating the box in your mind if a line doesn't fit the first way you look at it.
For the three themed boxes, only pull titles from the list that already match the required theme, so the theme constraint narrows the title choice rather than blocking a drawing altogether.
If a title genuinely cannot be made to include the given lines as a real part of the drawing after trying a few orientations, swap in the next title on the list rather than forcing a mismatch.
Finish each box by rendering the chosen scene neatly in pencil, keeping the original lines clearly part of the final image, and keep the title as originally planned or refine it slightly to match the finished drawing.
Working title-first this way tends to produce a more varied set of ten ideas, since the titles are chosen for variety before any drawing constraint narrows the choices.