transclude, require, link and $ctrl need proper explanations before a lab assignment.

This lab's given solution does not track with the readme. The readme says as follows:

Using what you know about directives so far, make the tab component add itself to the tabs list of tabs. Then, display the tabs labels at the top.
Using ng-click, allow the user to click on the tabs label to make it swap what tab is active. Hint: change a variable in the parent controller to what tab label is active. Then, in our child tabs, use ng-show to check the parent controller's value against the tab's label.

The solution does not use ng-show, it uses ng-if. Also, the solution requires using aspects of the link function that have not been introduced at this point in the curriculum. So, I feel the "using what you know about directives so far" is not really correct here.