Suggestions from ESLgold:

Low Beginnning

Focus on simple information exchange, expressing thoughts and asking questions
Types of Materials: Texts with simple language structure and basic vocabulary

High Beginning

Focus on using language to accomplish simple personal objectives appropriately
Types of Materials: Texts which encourage interaction and learning of practical phrases

Low Intermediate

Focus on general discussion of a variety of topics and functioning well in social situations
Types of Materials: Texts which enable both structured and free discussion and role play

High Intermediate

Focus on elaborating and supporting opinions as well as simple formal presentations
Types of Materials: Texts which engage students in thought-provoking interaction

Advanced

Focus on formal presentations, polished conversation skills and idiomatic expression
Types of Materials: Texts providing a variety of situations for in-depth expression