Here are some catechisms that might be useful for parents:
The Westminster Shorter Catechism, with scripture proofs.
A Small Children's Catechism, by Chris Schlect.
I Belong to God: A Covenantal Catechism (PDF) by Rich Lusk.
A Trinitarian Catechism in the form of a poetic chiasm, by Douglas Jones.
I’m also working on a situational catechism for my children.
See also the incredibly funny Semi-Pelagian narrower catechism.