There is actually a community place here that benefits children and families in our specific school district. I just dropped off a donation of nonperishable items and was told this was the time of year they really needed it...so a food drive of some sort comes to mind.
Habitat for Humanity will not let children work on houses, it's obviously a safety issue. But they will allow kids to help plant flower beds when the houses are complete and ready to turn over to the families.
Coat drive. It's getting warmer, but people could benefit next winter. And many people are purging things now during spring cleaning.
Similar to the other class, but collect books for a local children's hospital.
Maybe a mentoring program of some sort. Match your kids with younger grades and practice reading or math skills.
I would also brainstorm with the kids. They may have an amazing doable idea! GL!