Drawing what you already have.....
Making Thumbnail Designs
After you have the objects drawn that will be in your obstacle course design, draw 4 or more plans that will utilize what is in your backyard. Draw the objects that can't move first onto each design first... such as Trees, Rocks, Sheds, Patios, etc. After you have those objects drawn in, you can then try different arrangements of the movable objects such as sticks, chairs and water hoses.
Finally, draw the arrows and the directions of movement and draw write in the activities that you are supposed to do.... skip, jump, run, hop, etc.
Have fun doing your obstacle course designs!