The easier Beethoven sonatas are quite lengthyNo not the moonlight sonatatry Op. 49 no. 1 and 2
Most Mozart sonatas are very manageable for intermediate students. Mozart KV 333, for example, is very easy - you should be able to sight-read it with few errors. It has crunchy harmonies in the middle of the first movement, as well as a nice cantabile second movement, so it's definitely worth a try....