Assess educators' ability to evaluate students' analytical understanding of decomposing whole numbers 1–20 into all possible unordered pairs and triples using manipulatives and visual models. Tasks: for selected target numbers, require students to enumerate every distinct pair and triple partition (order not counted), build each partition with counters/cubes/ten‑frames, create a matching visual diagram (number bond or bar model), identify missing addends, and explain observed patterns (commutativity, complements to 10, partition counts). Include rubrics for completeness, accuracy of representations, and explanation of reasoning.