I don't know how old your children are, but a good one for littler ones (even up to 10 or so), would be Leading Little Ones to God. Lots of basic Bible learning and talks about salvation, and principles of godly living. A good place to start with younger ones.
We've used:
Leading Little Ones to God
Training Hearts Teaching Minds
Mighty Acts of God
Stories with the Millers (there are quite a few in the series)
Building on the Rock series of books
These are just some that are coming to mind, but we always followed them up with Scripture reading and verse memory. That probably sounds time consuming, but it really only takes a few minutes.
Hope that helps! Blessings on your Bible studies!

Lisa ~ Gal. 2:20, Prov. 3:5-6
Mom to five great blessings

Ds23 - Graduated from HOD!
Ds21 - Graduated from HOD!
Dd19 - Graduated from HOD!
Dd17 - US History 2
Dd16 - World History
Loving HOD since 2010!