Hi hi, you can take a picture without a memory card and you could see it for at least 2 seconds(with a notice that says memory card not inserted).
But after that the picture will not be saved, it will disappear.

If there's an internal memory then it'll be kept.
But usually there's none for usual cameras like mine.
So you better find a memory card, fast! ><
Since it's a field trip you would probably need 4GB. 2GB is okay but from my experience I could only take pics for half of the day.
