Couple of things which really worked with my DS6

1. Copy some text word to word on paper from any book.

2. We invented a game, we put a timer for 1 min, then we take turns to suggest a topic, e.g. colors, then we both start writing as many colors we can in a min. In the end whoever gets more names on the paper gets a point and we continue. When we started with the game my son was able to get 2-4 words and now he is anywhere between 8 to 10 words :-). He enjoys going wild with the topics too.