Problems that will be offered in this course will vary in difficulty. Some of them will be intentionally simple exercises, while others will allow for solutions at different levels - from simple estimates or plausibility arguments to involved calculations. Students are advised to start with the former and then proceed to the latter as far as necessary and/or their current level allows. Collective work on the problems is strongly encouraged; however, each student has to turn in an individual write-up. Problems will be generally related to the material covered in class; however, sometimes they will intentionally lead or trail the lectures. On several occasions, we are planning to assign homework problems that will require reading textbooks on your own on topics not covered in class.