He is a good writer and he writes well – Adjectives and Adverbs

Some students struggle with the difference between adjectives (beautiful) and adverbs (beautifully), as this distinction is not always made in other languages. A good rule of thumb is the following: 
Adjectives usually refer to nouns, as in: “a nice lecturer”, “an interesting book” or “a busy afternoon.”
Adverbs refer to verbs and the way something is done: “she reads slowly”, “he answered badly”, “he listens carefully”, “she intervened successfully.”

For more detailed explanations and exercises, have a look at the following pages:

A very detailed explanation that is linked to two exercises.

This page explains the use of adverbs and adjectives with the help of academic texts. 

Quizzes to practise. 

Irregular Forms

Further problems arise from irregular forms and verbs that can be used both with adjectives and with adverbs.

Find a list of adjectives and adverbs that have the same form and adverbs that have two different forms. Linked to an exercise. 

Another list of irregular forms with example sentences. 

This page explains why some verbs, such as ‘to look’ or ‘to smell’ can be used with adjectives as well.