Breakdown of Der zu lesende Artikel ist wichtig.
sein
to be
lesen
to read
wichtig
important
zu
to (infinitive marker)
Questions & Answers about Der zu lesende Artikel ist wichtig.
What is the grammar behind zu lesende in this sentence?
This is the Gerundivum, which is exactly what your current lesson covers. You form it by putting zu in front of the present participle lesend. It translates to a passive obligation, meaning 'that must be read' or 'that is to be read'.
Why does it have an -e at the end?
Because it is acting as an attributive adjective describing Artikel. Since Artikel is a masculine noun in the nominative case and follows the definite article der, it takes the standard weak adjective ending -e.
Could I leave out the zu and just say der lesende Artikel?
No, because a standard present participle without zu has an active meaning. der lesende Mann means 'the reading man' (the man who reads). Since an article cannot read itself, you must add zu to give it that passive 'needs to be read' meaning.
Is there another way to say this if I want to avoid the Gerundivum?
Yes, you can expand it into a relative clause. You could say Der Artikel, der gelesen werden muss, ist wichtig or use the structure with the verb to be: Der Artikel, der zu lesen ist, ist wichtig. The Gerundivum is just a more compact, slightly more formal way to say the exact same thing.