The parenting theory du jour is one of those. On the other hand, abusive parents often learned that theory from having it practiced upon them when they were children. Of the two, I'll take the first over the second every time.

I agree that adoptive grandparents would help fill the need for mentoring and support.

What would be helpful in a class:

-Knowledge of stages of child physical development. The better to know what range is normal, and what might need intervention.

-Knowledge of stages of child psychological development. Inappropriate discipline that becomes abusive often comes from unrealistic expectations of the child's ability to understand by parents who have little understanding themselves.

-A basic menu of creative play ideas, also at an assortment of developmental levels, that one can do on a budget of nearly nothing. There's a ton of this kind of stuff, but I find that, even among the educated, it's becoming a lost part of folk knowledge.

-Specific information about child nutrition. Children don't belong on no-fat diets when they're little (fat is essential to brain development), but we can all cut out the sugar.

-Reading readiness and cultural literacy knowledge. For instance, I know the tunes to lots of nursery rhymes because they were sung to me when I was little. People think I'm a walking encyclopedia of this kind of stuff, but I only know it because I had grandparents who sang to me and read me rhymes. It's appalling how many people don't understand the value of music and poetry to language development, and no longer know these simple things.

-Checklists of behaviors for parents to cultivate when dealing with their children. Such as: Present them with choices when possible. Praise them often for things they do well. Talk to them. Take them for walks. Read to them, or, if you can't read well, borrow picture books with CDs from the library.

Did you know that according to research:
In a typical conversation with a 3 year old, an adult uses nine rare words per thousand.
In conversation with a 10 year old, the number jumps only to 11.7 words per thousand.
Guess what happens in a children's picture book? There are 30.9 rare words per thousand. Looks like nothing beats reading aloud to a preschooler!

--from School Library Journal, July 2006, pg 26. First Steps: "It's a Gift to be Fancy".

Something like that would be a good start to any potential parent, without the hazards.