Interesting. I would be inclined to just say 'Take out a piece of (notebook) paper' and not mention whether it comes from a pad or a notebook. Especially if the students are still learning English, simpler may be better.
stoffel, you don't say in your profile where you're from or where you're teaching, but there are evidently a few cultural differences. In US schools, in my day, students usually were taught to use loose-leaf notebook paper for assignments. Spiral-bound notebooks were only for taking notes that could stay in the notebook, because teachers didn't like all the little torn-off edges. I wonder if loose-leaf paper perhaps just isn't even used much in Europe, since LEO doesn't have an entry for it.
I was trying to think what makes the difference between a pad and a notebook. I think it may be that a pad is bound at the top, across the narrow edge, while a notebook is bound at the side, along the long (left) edge. I would call a steno pad, for instance, a spiral pad, but according to the pictures online, I would call a Collegeblock a spiral-bound notebook, if the distinction mattered.
Probably all this is becoming irrelevant in many countries now, as more students are able to use computers in class. I don't know if US students still ever write on paper much at all -- apparently many of them have never even learned cursive.