The sentence is correct Sam, and is something a native speaker would say. Great work!

Say it like Stan Laurel: "And our wives will be none the wiser!. . . hmm!"

It means.............knowing no more than before.

I beg to differ Kate. "none the wiser" is still a much used and perfectly acceptable expression. Perhaps it's not so widely used in the USA but in the UK it's still going strong.

The expression "none the wiser" is an expression that is still used today. It's not outdated. As someone else here said, it simply means that you don't know anything now that you didn't a bit before now. In other words, the amount of knowledge you have about something PRIOR to the lecture (in your example) is the same amount of knowledge you have AFTER the lecture. Guess the lecture wasn't very informative! Keep up the great work!