Exercises are offered to our Citizen members. They contain a set of instructions, assignment,s and criteria that should be met by those participating in the exercise. Submissions are then reviewed by the community for peer feedback.
View available Blender Exercises: https://cgcookie.com/categories/3d/exercises
It can be simple to break up the day from watching a ton of CG Cookie videos, or something extra to challenge yourself. In the end they're meant to test what you've learned and mimic real-world scenarios working as a digital artist.
At a job or contracting somebody will give you a set of constraints to complete a task, they will then critique and give feedback on what you've submitted. This is the artists way. Exercises are a great practice tool to see how you perform in this scenario. The only missing component is the time restriction, but that is something you could practice by giving yourself a certain timeframe to complete the exercise.
As an artist, your work is constantly being judged and critiqued by those around you. Exercises are meant to mimic this. Instructors may also vote on an exercise but due to the vast amount of submissions may not be able to review all of them.
As a member of CG Cookie, you're able to build up your feedback-giving skills by visiting other members' exercise submissions. Offering your impression of their submitted work and a constructive citizen or praise to the member.