Mouth wounds bleed a lot, but they're usually not as bad as they look. Try to keep your child (and yourself) calm -- a hug and a quiet voice go a long way with kids. There's no need to call the pediatrician unless the bite goes all the way through. Just:
1. Rinse her tongue with cold water if there's dirt or food in her mouth.
2. Apply cold pressure with ice or -- even better -- a frozen fruit bar. (If her tongue is still bleeding after 30 minutes, call the doc.)
3. Offer soft foods for a day or two, and try to avoid anything acidic.
4. Be patient. Most wounds heal within seven to ten days, and it's rare for tongue bites to become infected.