> I have realised that part
> of the assignement for Lesson 3 included lesson 4. And the actual
> assignement 4 seems to be for lesson 5. This has alomst caused me some
> confussion because the above do not correspond to the dateline for the
> assigments.

You should not confuse "chapter" with "lesson". Lesson 3 has two
chapters: chapter 3 & 4
Lesson 4 continues with chapter 5. The assignments always correspond to
the lessons, not the chapters.