Is it normal for a3 yr old to grind her teeth all the tune?

Not Really: Kids will be kids, but grinding is not a "normal" thing for kids to do regularly. I have a child, and at times she does do this, maybe once a week, that i see. I talk to her about the damage she could cause and that it will be forever. She gets the point, i think, but i don't make it seem funny, amusing, or otherwise something she should do for attention. Maybe why god gives us 2-sets of teeth!

Yes: Most young children grind their teeth. It is usually the subconscious effort of the brain and growing facial bones and muscles to find harmony with themselves and the teeth. I know it drives you crazy and sounds awful, but be patient...It will go away!