It's important that we incorporate writing into EVERY subject! At my school, each subject takes a week and a Wednesday and creates several writing topics on which students will productively write. Not only are they exercising their writing skills, they are putting their knowledge to the test as they answer the prompts.
These prompts are based on our Forces unit. You could modify them any way to make them more or less challenging. Often, I will use the prompts at different stations and have students rotate through until they've answered them all.
Please contact me with any questions!