Being such a low value it won't be electrolytic or tantalum. This cap should have high leakage resistance so that its leakage won't affect the feedback circuit. Of course the 1 meg resistor swamps that anyhow. You can use a ceramic cap (cheap) or a polystyrene cap if you want. There are probably others just as good, I'm just telling you what worked for me.
That's true for critical or sensitive applications. But for the purposes of his homework/lab work, a ceramic cap should work fine. He is unlikely to notice the small temp coefficient or non-linear effects.