After you teach the language how do you reinforce it?
For this kind of language I like to do a lot of survey and role play type activities.
Survey: Have students write down 5-10 activities they want to invite other students to do with them. Then have them make a chart like this:
Code:
activity _____|__name1__|__name2___|__name3__
play soccer___|_________|__________|_______
see a movie___|_________|__________|_______
play cards____|_________|__________|_______
Then they go around asking students if they want to do that activity with them and the other student can accept or delice. The "asker" writes yes or no in their chart.
Role Play: Create situations and conversations that students practice and memorize. These are best if their funny. I usually let students write their own conversation where, say in this example, three offers are made and all three of them are refused. Have them memorize their conversations and then practice them in front of the class.
The key to remebering and using the language is to get them to practice it over and over until it becomes natural to say.
hope that helps
eric