Formative assessment involves providing students with continual, explicit feedback to help them track their learning progress. It helps students answer questions about where they are in their learning, where they need to go, and how to close gaps. Effective formative assessment uses learning progressions, short-term goals, clearly defined learning goals and criteria, and descriptive feedback tailored to individual students. Strategies for formative assessment include clinical interviews using math problems to assess understanding, allowing time for self-assessment and making connections between concepts.