The interaction from your post demonstrates a key principle to teaching almost anything: ask them to explain what they think you said, and listen carefully to the response: it will tell you precisely what needs to be corrected.

I shamelessly stole copied this trick from my math tutor some 25 years ago, and it has not failed me since. I used it in class during my brief stint as a teaching assistant, at work when talking about software design, and with my eight year old when talking about her school assignments.

Of course you cannot always be blunt about asking them to repeat what you just said, so you need to adjust your strategy. For example, here is how I would re-phrase your follow-up statement from the OP as a "probing" question:

I like your idea of creating an extension method, but I don't like how you passed a large complex lambda as a parameter. Do you see how this complex lambda forces others to know too much certain things about the method's implementation?

This question is impossible to answer correctly without understanding the issue that you are trying to highlight. I found that ending my explanations with a question that requires analysis of what I just said speeds up the learning process, and gives me feedback that I need to make corrections.

The interaction from your post demonstrates a key principle to teaching almost anything: ask them to explain what they think you said, and listen carefully to the response: it will tell you precisely what needs to be corrected.

I have shamelessly stolen copied this trick from my math tutor some 25 years ago, and it has not failed me since. I used it in class during my brief stint as a teaching assistant, at work when talking about software design, and with my eight year old when talking about her school assignments.

Of course you cannot always be blunt about asking them to repeat what you just said, so you need to adjust your strategy. For example, here is how I would re-phrase your follow-up statement from the OP as a "probing" question:

I like your idea of creating an extension method, but I don't like how you passed a large complex lambda as a parameter. Do you see how this complex lambda forces others to know too much certain things about the method's implementation?

This question is impossible to answer correctly without understanding the issue that you are trying to highlight. I found that ending my explanations with a question that requires analysis of what I just said speeds up the learning process, and gives me feedback that I need to make corrections.