You might find useful to copy the source code of all the examples from the textbook and use it for practice. The code is divided by chapter as follows: ch1.scm, ch2.scm, and ch3.scm. The files ch2support.scm and ch3support.scm contain procedures from other chapters that are needed to run the examples. The file ch2tests.scm shows examples of calling some of the procedures in Chapter 2. Enjoy!