DLS course 4, Error in week 1 exercise 1

Yes, as Tom says, what must have happened is that the update didn’t happen in the correct way. Check the “Get a Clean Copy” procedure on the FAQ Thread. Please follow those instructions and then let us know if that doesn’t fix the problem.

Since you are new to DLS, it would be worth at least scanning through all the other items on the FAQ Thread so that you know what is there. You may not need all of them right away, but there are at least a couple that are relevant to how the notebooks work. Normally one would get that familiarity from the assignments in the earlier courses.