Create a simple design on graph paper, such as a Christmas tree. Confine the design within a 15-by-24-square area. The drawing must contain no curves; each line can go through a square horizontally, vertically or diagonally, but always crossing two of its corners.
Draw another similar design, this time drawing a Cartesian coordinate plane over it. Depending on the math level of students, include all four quadrants or just design the first quadrant of the coordinate system.
Equip each child a sheet of graph paper. Instruct them to number the top row's first 15 squares -- excluding the corner square -- from left to right. Tell them to use alphabet letters on the leftmost column's squares -- again excluding the corner square. You can also print the grid on white paper on your printer, adding the letters and numbers yourself.
Show how children can name each square using its letter, followed by the number. For example, the square falling in the 10th column and third row is J3.
Give step-by-step instructions to students on how to make a drawing. For example, say "on A7, form a line on the square's top side" or "paint the square between K3, K9, O3 and O9 red." At the end of each step, check if every student has followed your exact directions.
Distribute another set of graph papers to students. Show them a sample of a Cartesian plane on a graph paper and ask them to copy it on their own sheet.
Explain that finding the coordinates on the plane requires the same steps students followed before with the letter and the number. If students are old enough to understand negative values, explain the concept of the four quadrants as well.
Give instructions on a new design, this time using coordinates, such as (2,3) instead of B3. Expand the design in all four quadrants, if you have already introduced them.