Lecture vs. course

The words lecture and course are both used in connection with education. Consulting the Oxford Learner’s Dictionaries, we have

lecture = a talk that is given to a group of people to teach them about a particular subject

and

course = a series of lessons or lectures on a particular subject.

Especially German native speakers often struggle to distinguish between lecture and course because both translate to Vorlesung. For example, you will often hear people say

I’m teaching a lecture on …

even though they are referring to an entire semester and should therefore say

I’m teaching a course on …

PS: Check out this post about other common mistakes in connection with lectures.