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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. For an example, see Fig.~\ref{f.sample-handout-page}. Sketches for the handout, as shown in Fig.~\ref{f.sample-handout-page}, are made using the \href{https://evernote.com/penultimate/}{Penultimate} app on an iPad.  Fig.~\ref{f.sample-handout-page} also demonstrates how exercises are built into the text. Typically a few exercises  are assignedas ``reading exercises,'' to be completed  prior to the start of lecture. lecture as guides to reading the notes.  Longer, more involved problems are 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, and the solutions are discussed in lecture.