Superlative adverbs are adverbs ending in -est. So think of big, bigger and biggest. Biggest is the superlative adverb due to the it ending in -est and having the 'superior' effect which is linked to its name of superlative.
Sprint is the fastest run is fast but not as fast as sprint
1=sprint
2=run
3=jog
4=trot
5=stroll
Did our teacher say the due date had been extended?