A short one but a good one!
I learnt about this while I was in teacher's college as a strategy to help students explain an idea/concept/etc. in a short sentence. I've used this strategy in high school and now I often use it in primary school and students find it exciting and a challenge.
It is called a $1 sentence and each word is worth 10 cents. Students are asked to respond to a question or summarise a passage in a one dollar sentence (ten words only!).
Try it out!!! Trust me it is wonderful!