There is a great deal of research that suggests taking a quiz immediately following a lesson SIGNIFICANTLY improves long term retention of the information. https://en.wikipedia.org/wiki/Testing_effect
Thus, we encourage you to take the following quiz. Note, these questions are difficult and you should not worry if you get them wrong. These questions go beyond what was taught during these lessons, and so you should not feel like you didn't understand the material just because you got many of these questions wrong. Just take the time afterward to review the explanations of the correct answers (the feedback will be available after you submit the quiz). The act of taking the quiz goes a long way towards helping you retain this information. We made the questions difficult so that you can learn something new from the answers.