I really hate exercises.  Not the activities.  Just the word. That's one of the things I learned in school.  There were always exercises at the end of the chapter.  I could ignore them, of course, unless the teacher assigned them.  But assigned or not, they didn't seem to have much connection to real life.  And the teacher always knew the correct answer.   Which also didn't seem to have much connection to real life. 

The Thinkerer has some pages that people might call exercises.  Nobody assigns them.  Nobody knows the correct answer.  And any of them that you do will have a close connection to your real life.  So I don' t think they really count as exercises. They are more like something to do to get the rest of your brain up to speed on what you read.   Feel free to use a different name.  S. E.

'When I use a word,' Humpty Dumpty said, in a rather scornful tone,' it means just what I choose it to mean, neither more nor less.'

'The question is,' said Alice, 'whether you can make words mean so many different things.'

'The question is,' said Humpty Dumpty, 'which is to be master - that's all.'

Look at what it is, not what it is called. 
The name is just how you talk about it.