The material on the course platform consists of text, different types of questions (e.g. multi-choice and free-text), and coding exercises. As you have seen already, the contents are presented in “blocks”. The green dot in the top left corner of a block (like this one) means that, either there is no question associated with the block, or that you have successfully completed the exercise given in the block.

If, instead, there is a red dot in the corner, that means that you need to answer the question correctly and click Submit to store your progress. As mentioned above, this requires that you have signed in. If not, a log-in window will pop up when you press the submit button.

Try it out:

As you can see, you will get feedback on your answer right away. If your answer happens to be incorrect you can simply try again. Please take the feedback into account and think about why the answer was incorrect, though. It is an important part of your learning!