By this time you must have a valid account on Code Lab. Do login to the Code Lab site and work through some of the problems assigned from Chapter 4. Do not re-register, at this site if you have already done so.
Here are some of the problems that I would like you to try from those exercises:
You may try the problems as many times as you like. There is no negative grading and you do not have to submit anything. As long as you used your actual name to register we will be able to identify you.
If you are stuck on a problem come and get help from us during our office hours. Check the office hours location and times in the syllabus.