Some resources for critical thinking exercises are About.com and Teachnology. Additional resources for critical thinking activities are Minds in Bloom and Problem-Solving-Techniques.com. These resources offer the exercises for free, as of 2015.
About.com features critical thinking exercises that are designed to help students improve their critical thinking abilities. Teachnology provides printable worksheets with critical thinking activities for students. These worksheets feature themes such as compare and contrast, brain teasers and logic puzzles.
This type of thinking is difficult for some because it requires the student to set aside any personal beliefs or assumptions. It also requires the student to understand the difference between facts and opinions, explains About.com.