Here are some great resources:

This book (not free) is my favourite for learning how to use Smalltalk for object-oriented programming: Smalltalk, Objects, and Design, by Chamond Liu.

I myself have published a whole bunch of Smalltalk tutorials. The latest ones are:

IMPORTANT UPDATE: There is a new Pharo MOOC that starts on October 16th, 2017. Sign up now!

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