How old are the pre-schoolers? Do you need themed ideas? What are lessons and themes that you have coming up? Are you with them by yourself? What type of setting? Sunday School? Children's Church? Nursery?
This age group is my biggest challenge...I call them my problem group...not because the actual kids are, but I have more difficulty writing the curriculum for this group than the others.
When you have them for as long as you do, VARIETY is a key word. They will definitely need many different activities.
Music
I know our preschoolers like the music videos where the kids sing and do motions and such. You could always start with one of them...pick a few songs...do the same ones for many weeks in a row. Also, you can come up with little songs or poems with motions.
Prayer
I would always make sure that prayer is included a couple times at least during the time. Our preschoolers like to pray aloud and will volunteer in our opening.
Story
Preschoolers like stories. You can find good story books with nice pictures written on their level retelling a bible story. Felt boards are nice...they like those, and you can tell the stories with them. Have a charater from the bible story visit and tell the story. or example...story of Ruth. Ruth can visit the classroom and tell the story with props. No men for Moses?? Miriam can tell...or just a lady who was in the Exodus.
Movies
I don't advocate for children to be sat in front of a tv and left. However, their are wonderful videos that tell the story in a wonderful way. We use videos and also discuss afterwards...or even stop during the movie. No movie we use is more than 30 minutes. You could also serve popcorn and a drink to make it a "movie" experience.
Coloring
Always have crayons and paper or coloring pictures specifically for their age.
Art
Our kids like to create art projects. They usually need help with cutting, but they like gluing and creating!! Love stickers!!
Games
The kids love games, too. I guess if I knew more specifically what lessons you will be having, I could provide more specific games. This Sunday the preschoolers bowled. Bought a plastic children's bowling set at KMart (7.99 but this Friday it is 4.99). They needed to answer a question to do with Daniel and the Lion's Den before they could bowl. They loved it! Also, you could play Duck, duck, goose...only change it to ....Lion, lion, Daniel...or Aaron, Aaron, Moses...and so on. During the summer...we had a giant Goliath...water balloons...the kids answered questions and then they could be David and throw a balloon at Goliath. They loved that, too...of course...that is outside.
Play time
For this age and the amount of time you have, I think just having a play time would be important. They are going to want to be up and moving...and having play time will also help in their creativity and social skills.
I could add more, but this should help you a little. Feel free to PM me or post here any lessons you have coming up, and I could send you some more specific ideas.
Blessings to you for your work!