I think it's a great idea! When my kids were younger we would have a big clean-up of clothes, toys and household goods for the two charities I support in South Africa. One is a "children's village" which houses multiple children in a "unit" instead of dorms, so they get the experience of living in a family unit. The other is Little Eden, a home for severely brain-damaged children.

My kids always came with me - sure the first time there were lots of questions, and lots of explaining to do. But I found that it gave them a greater appreciation of their home, and their possessions. They were also less reluctant to "give up" their old stuff when they knew where it was going!

Just my opinion, but my experiences with this all had positive results!

Good luck, and let us know how it goes!