Assessment for learning is the process of seeking and interpreting evidence for use by learners and their teachers to decide where the learners are in their learning, where they need to go and how best to get there.
Assessment for Learning: Easy-to-use Checklists for Fast Assessment
Graphic that explains the different types of classroom assessment (I'd add importance of feedback to formative). Inspired by the book Mindsets in the Classroom by Mary Cay Ricci---Crockett's Classrroom
A activity card is a great formative assessment that can be conducted at the end of any lesson. The teacher can use students' answers to assess their understanding of the taught content and determine what needs to be further taught.
70 different activities, ideas or tools based around assessment for learning. Each comes with a description and a pretty picture to liven up your day. The toolkit is easy to navigate and the ideas are transferable across key stages and subjects.