This isn't strictly just about the Old Testament, but I think the OT comes off worse in the Sunday School kind of Bible Teaching... John Walton on Hermeneutics and Childrens Curriculum, ht: Milton Stanley.

Walton observes five disturbing traits:

Promotion of the Trivial
Illegitimate extrapolation
Reading Between the Lines
Missing important nuance
Focus on people rather than God

And concludes: If we are negligent of sound hermeneutics when we teach Bible to children, should it be any wonder that when they get into youth groups, Bible studies and become adults in the church, that they do not know how to derive the authoritative teaching from the text?Teaching the Old Testament seems to be tricky but surely the key is to let the text contrain us. We're only at liberty to teach what it says, in it's context, within the boundaries and rules that it sets out for us. Then, and only then, will we hear God speak with authority. An authority that will be unavoidable, piercing to the heart and leading to genuine transformation to Christlikeness, or to hardening of our hearts as we're confronted by God the Father, Son and Holy Spirit, who has all authority.