When you're done putting together all the pieces yours should look like this. This particular bridge was able to hold the maximum 30 pounds.
The objective of this project was to build a bridge using nothing but school glue and toothpicks. Our teacher have us credit for just simply building a bridge but gave us extra points for every pound it held with the maximum being 30 pounds.
First thing you would have to do is figure out which bridge design you want to go with for the main part. I decided to go with the Warren (with verticals) design but you should choose one that would be easiest for you or the one you think would hold up the best. I used this paper as reference of the different types of bridges I could build. The one I chose to build is in the third row third column.
Gather your materials. Any kind of toothpicks will do I got mine from walmart. My teacher made it a requirement to use only school glue so specify with your teacher as to what type of glue you could use.
Start to sketch out your design for the bridge. Make sure to make a sketch for your main bridge and the base that will hold up your bridge. The image depicts the sketch I made for the base of the bridge. I would recommend using grid paper to draw your sketch on so you know that the size and shape will be accurate. I got the print out of the grid paper from http://donnayoung.org/math/graph-paper.htm and I selected the 30 X 40 one.
Now in this step I would suggest you place wax paper over your design so that you wont have to draw your design again and you wont have to rip your toothpicks off your paper.
I used a wire cutter to cut all the toothpick pieces accordingly. You will probably need parental supervision to use this tool. Or you could used safety scissors but that will also take longer and be more painful on your hands and might come out uneven.