Predict the result
Which of these source points lie on y equals two x minus three?
A point must satisfy the equation.

Set up the model
Substitute each x and compare the calculated result to its y-coordinate.
A matching y means the point is on the line.

Work the example
The point zero comma negative three and the point three comma three both work.
The point two comma negative three does not work, because two times two minus three is one.
The point negative one comma negative five also works.
The four results are yes, yes, no, and yes.

Check the result
Now test the point zero comma negative one and the point two comma five for y equals three x minus one.
Take eight seconds to think before the answer appears.
[Eight-second silent pause to work; the answer remains hidden.]
Both pairs satisfy the equation.
Both points lie on that line.

Interpret the result
Graphing and substitution describe the same set of solutions.
Use the original task and check that your result fits its meaning.