A common misconception with Year 10 students writing HTML is usage of heading tags. Many students incorrectly assume that <h1> is the first heading, <h2> the second and so on… Until they get to <h7> when they get an error. They have interpreted headings as a sequence… all with the same styling rather than hierarchical with <h1> a main heading with appropriate styling and <h2> a sub heading <h3> a sub sub heading and so on.
Just like Mathematics misconceptions it is important to identify and rectify as early as possible – or give an exercise that makes the meaning of heading tags obvious. After all I don’t want to see this error at Year 11… so I had better improve my teaching practice.