It is up to the parent to instruct the child in the ways of God:
Proverbs 22:6 Train up a child in the way he should go: and when he is old, he will not depart from it.
2 Timothy 3:14,15 But you must continue in the things which you have learned and been assured of, knowing from whom you have learned them, and that from childhood you have known the Holy Scriptures, which are able to make you wise for salvation through faith which is in Christ Jesus.
Here are links to some resources you might find useful in teaching the scriptures to children:
Christadelphian Sunday School Union: www.cssu.org.uk
Christadelphian Sunday School Association: www.cssa.asn.au
Australian Christadelphian Sunday School Union: www.acssu.org.au
I hope you have found this helpful.
May God bless you,