Jesus' robe of righteousness is Heaven's Uniform.
If your kids are in a school that requires a uniform or in a club, like Pathfinders, that has one you could use that as a discussion starter for Jesus' Robe of Righteousness.
Sometimes a kid can't afford to obtain the proper uniform on his own. That's how we are with Heaven's uniform. We simply can't be good enough to get to Heaven. We need to be covered with Jesus' robe of righteousness.
I wrote a story based on this concept which could help flesh out this idea. It's posted on our kid's blog. Click here to read it
There a lot of texts on this topic. You probably won't want to use them all with your kids but here's some of them for your interest.
Isaiah 64:6--Our righteousness is not good enough, it's like a dirty garment
Isaiah 61:10--Jesus is willing to give us His own pure robe of righteousness.
Zechariah 3--A story of God doing this.
Matthew 22:1-14--Heaven's uniform is a requirement
Revelation 19:8--We can't get the garment ourselves it's GIVEN to us by God.
Revelation 22:14--(NOTE the King James Version translates this verse very differently from most Bibles)