Science Buddies: "Ask an Expert"

The tracks aren't appearing and I've tried everything listed on the project page.

Sorry to hear it's not working. We may need more details to try to figure out what is going on.

What radiation source are you using?
If smoke detector, does it look like the one on the picture in the project guide?
Make sure to soak (not just wet, but soak!) the felt and close the lid quickly.
Warming the dish with your hands to make vapor is important. As is petri dish contact with dried ice.

It may also be that the tracks are there and you don't see them: Dark room, bright flash light, let your eyes get accustomed to the dark by turning off flashlight. Then aim the light onto the dish.

Let us know how it goes...

My Son has only had results with the needle alone, it didn't work wrapped in plastic wrap, aluminum foil, or cloth. Any suggestions???