Which of the following is a desirable strategy for assessing students'…

"Assessment for learning" (formative assessment) in mathematics education focuses on evaluating a student's reasoning process and conceptual understanding, not just whether a final numerical answer happens to be correct. A well-designed assessment strategy should reveal how a student thinks, expose specific misconceptions, and accommodate differences in ability and learning pace among students.

Asking students to justify their responses — to explain the steps and reasoning that led to an answer — gives a teacher direct evidence of the student's mathematical thinking. This is exactly the kind of information a desirable assessment strategy should capture, which is why treating students' justification of their responses as an important basis of assessment is the correct choice.

• Giving every student the same task regardless of their ability or readiness ignores individual differences and can fail to reveal what a particular student actually understands.

• Disregarding incorrect answers throws away exactly the information that shows where a student's understanding has broken down, information a teacher needs to plan further instruction.

• Leaving mathematical vocabulary out of assessment overlooks that precise terminology is part of how students organize, express, and communicate mathematical understanding.

Hence, among the given options, valuing students' justification of their responses as a basis of assessment is the desirable strategy for assessing learning in mathematics.