The hypothesis that the dust collected from all the locations will contain some micrometeorites has been proven to be true.
Micrometeorites pose a lot of danger in space exploration. The relative speed between a micrometeorite and an orbiting spacecraft can be very great, to the tune of several kilometers per second (not per hour). The spacecraft and the astronaut's spacesuit must be built to withstand any bombardment of micrometeorites. Continual high speed impact can compromise the safety and functionality of the spacecraft/space suit.
The science fair project may be repeated by collecting samples throughout the different months of the year and comparing the types of micrometeorite found.
The experiment may also be done by collecting samples after or during a meteorite shower.
Micrometeoroid - http://en.wikipedia.org/wiki/Micrometeoroid
Micrometeorites - http://bizarrelabs.com/met.htm