I believe that there should be a focus on problematic language issues such as prepositions in the language classroom in order to provide continuous exposure to such features. Consequently I provided my students with supplementary activities on prepositions, and also promoted learner autonomy by highlighting urls which deal with collocation. Analysis of the students written output shows the input to have been successful in focussing students' attention on this problematic language aspect. While a pre-input writing task generated 83 prepositional errors, at the rate of 1 in every 48 words, longer post-input tasks only generated 76 prepositional errors at the rate of 1 in every 215 words. Consequently, I plan to continue providing students with input on this often neglected language feature, in order to increase students' written accuracy.