deletions | additions       diff --git a/lectures.tex b/lectures.tex  index 5bdbb8a..d91ec00 100644  --- a/lectures.tex  +++ b/lectures.tex 
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it features tight integration of text and graphics, which reduces skipping back and forth; and  it implements margin notes, which we use for quick reminders of mathematical formulae and side remarks. A sample page, from the notes on coordinate systems, is shown in Fig.~\ref{fig:sample-handout-page}. Sketches for the handout were made on an iPad using the \href{https://evernote.com/penultimate/}{Penultimate} app.     As can be seen in Fig.~\ref{fig:sample-handout-page}, exercises are incorporated into the body of the notes. Typically we assign  a few exercisesare assigned  prior to the start of lecture as guides to reading the notes. Longer, We then assign longer,  more involved problemsare then assigned  as homework following the lecture. Solutions, which are written in the same format as the lecture notes, are distributed when the marked assignments are returned. The class discusses the  solutionsare discussed  in lecture, with ample opportunity for students to ask questions.