You need to collect oral and written grammatical errors that your ESL/EFL students make.  Errors are best understood if analyzed in context. Bring back written homework, journals and essays that your students wrote or just type up / write the errors you would like to include in your error database.  For your oral errors, either audio-record your students’ speech or take comprehensive notes so that you can capture the context of a particular utterance.  The focus of the assignment is on grammatical errors (not vocabulary, spelling or pronunciation).  For the various types of grammatical categories, consult the table of contents in The Grammar Book.

For each error, make sure you mark if it is written or oral, the L1 of the learner, their age, level of proficiency and even their gender. The more “data” you bring, the richer our explorations in EAL.