Sites like Resh Skysmart provide step-by-step solutions for the Vilenkin 5th-grade textbook, including theoretical questions and "Checking Yourself" sections that often feature these puzzles.
Definitions for "Ray" (a line with a beginning but no end), "Vertex," and "Segment".
Scribd hosts various PDF versions and supplementary materials for the Vilenkin curriculum that may include scanned puzzle pages.
While there isn't a single "article" dedicated solely to a crossword in the 2017 Vilenkin 5th-grade math textbook, this term usually refers to the found at the end of chapters or major sections to test vocabulary and core concepts. Key Resources for Vilenkin 5th Grade Crosswords