Nothin' to it, but FUN to do it!
A Few Ideas:
1. Mom and child/children work together to fill the three bags with red, white, and blue items.
2. Divide kids into teams (Red, White, and Blue). Meet back together to see who got the most or strangest item(s).
3. Do this activity in your house/yard. You'll be amazed what gets lumped together (like bubbles and painters tape)!
4. Do this activity in a store, such as Walmart (probably nix the bags though...don't want them to think you're shoplifting!).
5. Set a time limit per bag (say, 5 minutes) or required number of items per color (7, for example).
Any other ideas? Please share!