This kind of assessment sounds very time consuming. How do teachers manage it?

Looking carefully at student work does take time, but the simple fact of the matter is that if we don't look closely at that work, we have no idea what students are really understanding and what they are missing. And, without feedback, students have little chance of figuring out what they need to work on.

On the other hand, it helps to keep in mind that, in fact, most of us are assessing our students all the time. Every time they ask a question or respond to one of ours, we are thinking about what those questions and responses reveal about their learning. The trick is to figure out how to let our students benefit from that continual weighing process and to help them understand the criteria for that assessment as well as we do.

Several techniques help to make this more manageable:

1. Not every performance needs to be assessed formally. Feedback can be given verbally and informally as students work in small groups or as we lead a class discussion.
2. Keep criteria lists boiled down to just those few items that you really care about (those items stated in the understanding goals). Not only does this make the grading and feedback process easier for us, but it also ensures that students will be spending the time and energy well.
3. Take time to teach your students how to talk with one another about assessment. If everyone understands the criteria for a performance and has had practice with providing supportive critiques, the students can coach and provide feedback for one another, even if you're the one who ultimately gives the grade.

Understanding performances are the things students do to develop their understanding. Ongoing assessment is the process by which students get feedback on what they do, based on clearly articulated criteria for successful performances. It is, in essence, the process of reflecting on performances in order to gauge progress toward the understanding goals.