Diagnostic tests determine students' maths level and give them appropriate exercises taking into account their skill level. You can recognize a diagnostic test by the stethoscope symbol next to the chapter name, and a message: Start with taking a test to show what you already master.
Click on the text to start the test. The more exercises you do correctly, the more of the chapter can you skip.
Once you are done with the test, you can click on the "Submit" button at the bottom left of the screen.
You will get your results right away, as this test is graded by the computer. The results will show you how well you did each of the subchapters within a chapter:
When you go back to the home page, you will see that some subchapters are now open for you to click around. You might also see more stethoscopes next to some subchapter names- this means that you can do another diagnostic test in order to master that subchapter. This is only possible if your Teacher made it possible for students to repeat the tests.