Please keep going :)

Using Smalltalk (particularly Pharo) has been an eye-opening experience for me.

Its interesting to see that Amber has a Boolean class which I suppose corresponds to the JS boolean primitive. In other Smalltalks, I've seen a wonderful design where True and False are subclasses of Boolean. This way, there are no conditionals in the implementation of ifTrue: and ifFalse:

Yes, it is a great appetizer. However, that there are no navigation buttons quickly becomes an annyoance. I once pressed a wrong key and had to select ProfStef next. 10 times to get back to where I was :( One page (21?) seems to have a parsing bug.

You could just execute 10 timesRepeat: [ ProfStef next ], at least in Pharo.

on my Mac, control-p prints and control-d is a "DoIt."

That menu item is traditionally rendered in a sans serif font, so it look like "Dolt".

which browswer you used? on both Firefox and Chrome, pressing "DoIt" gives popup error "Cannot add self to a string."

Looks like you need to select only the line of code that you want to execute before you press "Do it". Works on Firefox for me.