I have a question about the
<thead> element. This element is suppose to contain data regarding table’s headings. However, in this example the second row also includes a heading
<th>Morning</th>, as well as the 3rd and 4th row which are not captured in the
<thead> element. How to deal with this situation?
Yes its a bit misleading,
Have a look at this topic where its discussed:
If th and thead are both headings in a table, what is the difference between them?
thead is essentially a box to hold your headings for the table. It is used along with tbody and tfoot to make up the entirety of a table - header, body, footer.
On the otherhand, th is a single heading element.
In this example given in the instructions for the table head exercise, the whole top row is the thead for the table. The bolded bits of text are each th elements.