Automatic recognition of non-native speech is problematic. A key challenge in developing spoken CALL systems is to design exercises that enable learning but which are still technically feasible. This especially applies to systems intended for practicing grammar. In the current paper we focus on the issue of matching design and speech technology. On the one hand we are developing and testing speech technology modules to determine what is feasible. On the other we use this knowledge in designing a CALL system for practicing pronunciation and grammar.