What's the Name of That Book??? discussion

Here's what I remember:
A boy was transported somehow to a primitive time period. For some reason I think this happened shortly after he kissed a girl or something. I think he could travel back and forth between modern time and primitive time. At some point he went back to modern time to bring modern items to the other world. I know he brought a flashlight. I think he also brought a remote control car (I'm unsure about this), and a couple other items I can't remember. When he brought these things with him to show the primitive people, they were amazed. At some point there was a war or fighting. The only other thing that I remember is that the primitive people discovered this clay that was explosive. I think it may have been red-colored. They would roll up the clay into balls and throw it to cause explosions, and they used it as a weapon.

I read this book maybe around 2007 when I was in junior high.

Thanks!

A Time of Darkness / Rocco by Sherryl Jordan?

(http://www.worldcat.org/advancedsearch > Keyword: boy primitive | Subject: time travel | 1980-2009 ? | Juvenile | Fiction | Book | English)

Lake, can you describe the primitive world, the people he met, creatures/animals he saw?

Fire Dancer?