By far the best solution for students without at pencil, in my own experience, has been the stubby, eraserless, “golf” pencils. Students know that they don’t even have to ask. If they don’t have a pencil, grab one. If they only have a mechanical pencil and a wooden one is more suitable for the task, grab one. If their pencil is dull and no sharpener is handy, grab one. The one drawback is that they may only be resharpened minimally before they are worthless.