#toothpick bridge

Dear followers: For my geometry class we have to build a bridge made completely out of toothpicks and glue. The requirements are that the bridge has to be able to have a five cm object fit under it, we have to have legs on the bridge that cannot touch the "water" (a 15 cm wide rectangle), and the base of the legs must fit into a 5x5 cm box on either side of the water. If you have ever done this before, I would love some tips. Even if you're just guessing, throw it out there. I've spent roughly 2 hours researching so far and plan on looking a little more into multiple bridge designs. Any suggestions?

Even though I only had a 4 day week, it seems more like 2935070 days. ;A; But I'm really stressed and this weekend isn't gonna be too great but still, at least I'm not at school. xD For my Physics class, we have to make a bridge out of flat toothpicks and I'm so bad with these kind of hands-on (and might I add delicate) projects. Ugh, I wish I could just buy one or something. I've never been good with crafts and stuff. Hopefully my dad will be willing to help because he's really good at these kind of things.