I wish somebody would build a Square Foot Gardening grid that you can insert into a raised garden bed to mark off squares, but until this is available, if you want to use the Square Foot Gardening method, you will need to devise your own method for marking off squares.
Lastly, connect your anchors using a heavy-duty string or twine, creating a grid-like pattern of planting squares. You can see an example of the results of this process in my garden bed here: Square Foot Planting Squares.
Once you have worked with raised garden beds for any of your gardening whether it is a flower garden, herb garden, or vegetable garden, you may not want to have an in-ground garden again because of how easy they are for cutting, maintaining, and harvesting. Your entire family will enjoy having some garden beds that are raised above the ground including your children.
Elevated garden beds are a good solution for plant drainage and compacting of the soil; plants will grow much better because of these facts. Raised beds will warm up faster in the springtime and continue to stay warm longer in the fall which means you can have a longer growing season.