What the standard asks
Grade 8 algebraic reasoning asks the student to identify and verify the values of x and y that simultaneously satisfy two linear equations in the form y = mx + b, from the intersections of the graphed equations. The solution is a point both lines share.
A two-minute check at home
Graph y = x + 1 and y = −x + 5 on the same axes. Ask where they meet. They should name the point (2, 3), then plug x = 2 into both equations and see that both give 3. If they can graph but cannot check, they have a picture without the meaning of a solution.
What it leads to next year
Algebra I treats systems as a main strand, including cases that do not intersect. 8.9 is the visual case with two slope-intercept lines.
This explainer does not claim that $100 for 100% lessons cover 8.9. It explains the Texas standard so you can check it yourself.