article: Classroom Data

(“Use classroom data to give systematic feedback to students to improve learning.”)
Here is the link.
Note: Data from the teacher about the class can go in two directions: to the students, and to the administration. This article is about the former, not the latter.
keywords: education, instruction, training, teaching, learning, study, curriculum, formative assessment, summative assessment, the sooner the better

closed under multiplication

Some sets closed under multiplication are:
the set of complex numbers
the set of real numbers
the set of polynomials
the set of primitive polynomials
the set of integers representable as the sum of two squares
{-1, 1}
keywords: Mathematics, Algebra, representation, Gauss’s lemma