Unzip the file for the class date you want, and use the preferences in Processing to make the unzipped folder your sketchbook. Note: in its effort to be “helpful,” the unzip feature in Windows might create a folder inside another folder. For example, if you unzip cit020_11_01_31.zip, Windows will create a directory named cit020_11_01_31, and inside it will not be the sketches, but instead another folder also named cit020_11_01_31. That inner folder contains the sketches.