Amazing, Wish every school had one of these. With proper lights and shadow, phases of moon and eclipses could be demonstrated so vividly. If it were elliptical, it could also show weathers, and earth's tilt would explain other variables.
Good job. But the moon should orbit the earth anticlockwise as the earth orbits the sun. If you put a twist into your string so it makes a figure of eight, it will then go the correct way. 🙂