One of the eight Mathematics Teaching Practices from Principles to Actions that needs to be a consistent component of every mathematics lesson. Effective teaching of mathematics consistently provides students, individually and collectively, with opportunities and supports to engage in productive struggle as they grapple with mathematical ideas and relationships.

“…productive struggle comprises the work that
students do to make sense of a situation and
determine a course of action when a solution
strategy is not stated, implied, or immediately
obvious. From an equity perspective, this implies that
each and every student must have the opportunity
to struggle with challenging mathematics and to
receive support that encourages their persistence
without removing the challenge.”

Boston, Melissa D., Fredrick Dillon, Margaret S. Smith, and Stephen Miller. Taking
Action: Implementing Effective Mathematics Teaching Practices in Grades 9-12.
Reston, VA: National Council of Teachers of Mathematics, 2017. [p.208]