Tape the paper to one end of the can and look through the other, Remember to have the correct side of the paper facing inwards. Astronomers tell us that the whole of the night sky in our hemisphere appears to slowly move around Polaris. Our tin can constellations may help. The pupils could take a can home and note the position of Ursa Major at say six o'clock in the evening, then check again at eight o'clock. As an extension they could find out if the position of the constellation was the same on Monday night at six o'clock as on Friday night at the same time.
Constellations do apparently move around the heavens.