I had the kids say the word "Priesthood" out loud to me and then I asked if any of them knew what that word meant? I explained to them that the priesthood is God's power. God gives the priesthood to older boys and men so that they can bless other people.
I showed them a few pictures of the priesthood being used, a baby's blessing, a baptism, a confirmation, a father's blessing, the sacrament, and I talked about how the priesthood was used in each of those pictures.
I also brought in a picture of my wedding and told them that when you are married in the temple you are married through the priesthood, and that is what makes our weddings sacred and different from other weddings. It is through the priesthood that our families are sealed together for eternity.
We had a crazy amount of kids in class and none of them were sitting and listening to my lesson, so I wrapped it up there with my testimony, but I had plans of doing a couple of other things.
I made this little book that I got from here. If I was really ambitious, I would have made one for each of the kids, but I thought the hand out from the manual covered it well enough.
I had planned to show this to them and review each one, using the flaps to try to get them excited about getting their own to color.