On a lark, I tried "Whence are you going, František?" This is probably an arguable case, but I submitted it for acceptance anyway. It isn't like I'm asking for "Whithersoever goeth thou, Fleance?" :p
In older English your sentence would have to use "whither" rather than "whence".
whither = to where
whence = from where
Whither goest thou?
Whence comest thou?
Also, with "thou" you want "goest/comest". The form "goeth/cometh" is third person.
Is "Kam jdeš, Františku?" also correct? And why yes/no? I'm helping myself with some online dictionaries while doing these exercises and "jdeč" was the correct form found there..
Is "Kam jdeš, Františku?" also correct?
Yes it is correct but not the same.
In Czech (as is explained in one of the lessons) verbs of movement contain information about how the movement is taking place (in English, verbs of movement usually emphasise direction instead).
In your example, you are using the verb jít, whereas the course uses jet. The former means going (or coming) on foot, the latter means going (or coming) using a means of ground transportation, such as a car, a horse or a bicycle.
And now my own question: if good old František is wheelchair-bound, jde nebo jede?
Sorry if I missed it in one of the lessons but I can't seem to find it again. What's exactly the difference between kde and kam ?
What's exactly the difference between kde and kam ?
Kde: Interrogative where without movement.
Kam: Interrogative where with movement towards.
— Kde jsi a kam jdeš? (“Where are you and where are you going to?”)
The third particle of interest is odkud (od + kde), used in the question “where from”:
— Odkud přijdeš, kde jsi a kam půjdeš? (“Where are you arriving from, where are you and where will you go to?”)