For example, after weeks of drilling on present progressive, students usually supplied both the auxiliary be and the –ing ending (for example, ‘He’s playing ball’). However, they also produced one or more of the morphemes in places where they did not belong(‘He’ want a cookie’). The same forms were produced with considerably less accuracy in obligatory context when they were no longer was being drilled instead. At this point, many students appeared to revert to what looked like a developmentally earlier stage, using no tense marking at all ( for example, ‘He play ball’ ). These findings provided evidence that an almost exclusive focus on accuracy and practice of particular grammatical forms does not mean that learners will be able to use the forms correctly outside the classroom drill setting, nor that they will continue to use them correctly once other forms are introduced.