I've written about friction lock projects before- like this table and this pole rack. This post a simplified friction locking pioneering bridge.
The purpose of this project is as an 'icebreaker' in a pioneering session - even Scouts who have no knotting experience can build one of these 'bridges', and feel that they have achieved something. A patrol will gain confidence from this exercise that will motivate them to learn lashings during the later parts of the training session.
This project requires 9 Scout staves or similar sized poles (bamboo may be too slippery), and the instructions show a sequence for the construction of the bridge (inspired by my favourite childhood toy, of course). Click on the image to enlarge it, and print the enlarged image. Step 5 is the critical one: your Scouts should pay careful attention to the placement of the two transverse poles, making sure they go over and under the correct poles.
Using only these instructions, all of the patrols in our troop were able to build one of these bridges. The fastest was built in about 2 minutes (admittedly this patrol had built one before) but I would allow 10 minutes for Scouts who have no prior experience. Here is the first patrol finished, with a Scout testing the sturdiness of the structure (please excuse my grainy camera-phone photograph):