Make a self supporting bridge with no mechanical fasteners or adhesives based on one of Leonardo Da Vinci's designs. You will be weaving the sticks together so that the tension between the sticks keeps the bridge together and lifts it off of the ground. You need:

Jumbo popsicle sticks (colorful ones may be easier)
Stable working platform
Patience

The bridge is strong when it comes to downward force but lateral force (from the sides) may cause it to topple. Moving the bridge while it stands (even slightly) could cause it to fall apart, so be careful.

Step 1: Four Sticks

Lay out 4 sticks like picture. You will be weaving the sticks from left to right. The two yellow sticks will be left the footings of the bridge.

Step 2: Add Sticks 5 & 6

Add two additional sticks (red) by weaving them under the green stick and over the orange stick. You may need to hold the orange stick in place while doing this. Notice the bridge starts to lift off the surface at this point. You will continually hold the bridge flat while you add new sticks, this will allow you to more easily add sticks without worry of your bridge tipping over/falling apart. TIP: It often helps to slide the new stick in at an angle to start with.

Step 3: Add Stick 7

Add a seventh stick (orange one) by sliding it underneath the two red sticks.

Step 4: Add Sticks 8 & 9

Weave sticks 8 & 9 (red sticks) under the orange stick and on top of the green stick. If you slowly let go of your bridge after you get these sticks into place, if will raise itself up so that the red sticks make a platform parallel to the ground. You can stop here or keep going to make your bridge longer...

Step 5: Add Sticks 10 & 11

Press your bridge flat again, this will help you keep tension on it while you add new pieces. Add on sticks 10 & 11 (yellow sticks) laying on the orange stick in the space between the outer and inner red sticks.

Step 6: Add Stick 12

Add stick 12 (green), in between red and yellow sticks as pictured. It should be on top of the yellow stick and under the red stick.

Step 7: Add Stick 13

Slide stick 13 (orange) underneath the yellow sticks, parallel to the previous green stick.

Step 8: Add Sticks 14 & 15

Weave sticks 14 &15 under the orange stick and over the green stick.

Step 9: Add Stick 16

Add stick 16 (green) underneath red sticks.

Step 10: Sticks 17 & 18 (last Two!!!)

Weave sticks 17 & 18 (red) under the green stick and over the orange stick.

Step 11: Ta Da!

Gently release the pressure on the bridge and it will rise up. Congratulations! Still want more bridge building excitement? Make your bridge longer, the more sticks you add the more the bridge will curve. How far can you build and still have a stable bridge. Remember: the bridge is strong when it comes to downward force but lateral force (from the sides) may cause it to topple. Moving the bridge while it stands (even slightly) could cause it to fall apart, so be careful. We've found the most successful way to move your bridge is to press it flat and slide it onto a tray/piece of cardboard. Have fun exploring engineering with this activity.

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