Keep track of how many Monarchs you see each day and note the date of the last sightings.
Graph tagged butterflies including tag number and date of tagging. Check tag findings at this
How many miles do the Monarch travel from your home to overwintering sites in Mexico? How long would it take?
Another great school project for an indoor setting would be a hydroponic raft. You could even grow the necessary milkweed for your caterpillar on a "lettuce raft" and create two projects in one! Access free plans for a raft here: Passive Hydroponics Plans.
Get a picture of a butterfly and put it on a transparency. Have the students use markers to color it. Put some tape on the underside of the body and stick it to a window (right) for a stained glass butterfly!
Draw or color life cycle of the Monarch Butterfly - egg, caterpillar, chrysalis and butterfly.
Have the students water color a white coffee filter, then bunch up the middle of the filter with a pipe cleaner for the body and antennae of the butterfly. You can these from thread or string.