Glue the top of the cereal box shut, then use a craft knife to cut a slot in the top of the box for valentine cards. (Parents will want to do this for younger children)
Glue the brown construction paper around the bottom of the box. You could also use a piece of green felt if you'd prefer the entire box be green.
Take your green felt and use hot glue to add it to the top of the box.
Use your craft knife (again, parents will want to do this for smaller kids) to cut a slit in the felt over the top of the hole. Fold the ends of the felt underneath, into the hole, using hot glue to hold it in place.
Use a pencil to make a circle in the center of the box. You can trace any household object to make your circle. I used a yogurt lid but you can trace a water glass, can of soda or anything else that you have on hand.
Use a pencil to add the rest of the soccer field markings. You can set your goals on the "field" to help with placement.
Trace over the pencil with white fabric paint.
You can also add partial circles to the corners to make it look more like a soccer field.
Finally, use hot glue to glue the goals and figurines to the felt. Let the white paint dry for several hours or overnight and then you're ready to collect some valentines!