Scientists don't know how many individual butterflies are in the monarch sanctuaries. For almost twenty years the scientists' best estimate was 10 million monarchs per hectare.

Then something happened...

• Read the Story! Find out what caused scientists to raise their estimate to as high as 50 million monarchs per hectare. >>

• Then Try Challenge Question #1: There are 4.61 hectares of monarchs this winter. If there are 10 million monarchs per hectare, how many butterflies are there? What if there are 50 million monarchs per hectare?

Answer: Try the question yourself! Then see how others answered. >>