1. Build the bridge on a piece of cardboard 15 cm by 35 cm (figure 1).

2. Draw a river, 15 cm wide, in the middle of the cardboard (figure 1).

3. Draw one 5-cm square at each end of the cardboard, 2.5 cm from the river and 2.5 cm from the edge (figure 2).

4. Draw and cut a 4-cm square exactly in the center of the cardboard, in the river (figure 2).

5. Draw plans of the bridge to show four views: the view from one end, the side view, the roadbed, and the top view. The plans must be readable, clear, and may not be changed once construction has begun.

6. When building the bridge, apply glue sparingly only to join the toothpicks.

7. The bridge must at all times touch only the cardboard inside the drawn squares. Toothpicks may be glued into holes punched in the cardboard inside the squares.

8. The bridge must be more than 5 cm high. This distance is measured from the cardboard to where the deck of the bridge would be. The tag board boat, 5 cm tall, must be able to travel the length of the river.

9. The bridge must be at least 4 cm wide. The tag board truck, 3.5 cm wide, must be able to travel the length of the road, if the bridge had a deck.