I think 2nd graders might be abit young for this technique - I did it with both 5th and 6th. 6th grade came out awesome, 5th was alright but not as good. I had them dip just the tip in the oil and then roll it on the side of the cup. We occasionally would pick up our paper to see if it was leaking thru.
I did it once with q-tips in second grade. Frankly, I didn't like the result. Maybe the younger kids had too heavy a hand with the oil. Janet ---