Beyond the scope of the quickstart tutorial, «other resources» of «Learn Fortran» lists a number of books and internet resources to get familiar (again) with Fortran. In comparison to the tutorial’s character inviting the interested to probe interaction with the language, I perceive both categories as static references.
The site in question hosts 6951 approved problems (kata) presented in an interactive, test-driven environment, grouped by difficulty (a little bit like learnlatex) of which 131 already are suitable for Fortran with automatic checks of the results. Because the problem sets are language agnostic (e.g., about basic language features, formatting, control flow, regular expressions, etc.), it is possible to compare how these are addressed in other languages, too. The successful solution then allows the users to discuss their approaches taken, and to score them for «cleverness» and «best practice»; or to adjust existing / create new problems to Fortran. It possibly could spur inspirations for packages of the Fortran package manager, too.