I am the lead of a small team where everyone has less than a year of software development experience. I wouldn't by any means call myself a software guru, but I have learned a few things in the few years that I've been writing software.

When we do code reviews I do a fair bit of teaching and correcting mistakes. I will say things like "This is overly complex and convoluted, and here's why," or "What do you think about moving this method into a separate class?" I am extra careful to communicate that if they have questions or dissenting opinions, that's ok and we need to discuss. Every time I correct someone, I ask "What do you think?" or something similar.

However they rarely if ever disagree or ask why. And lately I've been noticing more blatant signs that they are blindly agreeing with my statements and not forming opinions of their own.

I need a team who can learn to do things right autonomously, not just follow instructions. How does one correct a junior developer, but still encourage him to think for himself?

Edit: Here's an example of one of these obvious signs that they're not forming their own opinions:

Me: I like your idea of creating an extension method, but I don't like how you passed a large complex lambda as a parameter. The lambda forces others to know too much about the method's implementation.

Junior (after misunderstanding me): Yes, I totally agree. We should not use extension methods here because they force other developers to know too much about the implementation.

There was a misunderstanding, and that has been dealt with. But there was not even an OUNCE of logic in his statement! He thought he was regurgitating my logic back to me, thinking it would make sense when really he had no clue why he was saying it.