If you wish to read more about the teaching and learning of grammar, the following books may be useful:

Braidi, S (1999) The Acquisition of Second Language Syntax, Arnold, London
A somewhat theoretical, but nevertheless accessible, treatment of how grammar is acquired by language learners.

Doughty, C and Williams, J (1998) (eds) Focus on Form in Classroom SLA. Cambridge University Press, Cambridge
Provides a good overview of recent positions on teaching grammar.

Grauberg, W (1997) The Elements of Foreign Language Teaching. Multilingual Matters, Clevedon
One of the few books devoted specifically to the teaching of modern foreign languages, as opposed to EFL. It offers some excellent pointers for teachers of French and German, in particular.

Hinkel, E and Fotos, S (2002) (eds) New Perspectives on Grammar Teaching in Second Language Classrooms, Lawrence Erlbaum Associates, Mahwah, New Jersey
This volume provides a useful survey of current approaches.

Rutherford, W (1987) Second Language Grammar: Learning and teaching, Longman, London
A magnificent attempt to situate the teaching of grammar in a wider context that includes discourse skills, text development, and so on.

Thornbury, S (1999) How to Teach Grammar, Longman, London
This is a very good and accessible read, and serves as a fine introductory text.