This activity, adapted from Lessons for Algebraic Thinking, Grades 3-5 by Marilyn Burns, is a great introduction to plotting points on the coordinate grid for pre-HSE and even ABE students. As the name suggests, students are engaged in a game of tic-tac-toe. The lesson plan, including directions for setting up the game and student handouts, is included in the pdf link above.

We also have an adapted version of the game using x and y to label the axes. In this version, students mark their moves with a square or a triangle instead of X and O because of possible confusion between the marks and the x axis.