On the course's home page, an assignment link appears with its own icon, like this: . It is not immediately apparent to a new student that this icon means do this assignment. You might want to use a label to indicate that the assignment is something the student should do. In this example, a label instructs the student to complete the assignment and a multiple-choice survey question.
You can also label the individual activities with an imperative, such as "Read about the plants around you" or "Answer a ...