A variation on the wordless book - kids can color the pictures according to the directions, and have their own gospel color poster.
Gospel posters are a great way to display the message of salvation. Download this one (for FREE!) and post it in every classroom as a way to remind your kids (and your volunteers). 
Print it on any size card stock and laminate it so that it will last. You could even give one to each child to hang in their bedroom!