Children can learn about bridges by building models of them. They can build bridges out of materials such as balsa wood or even drinking straws. A simple challenge for kids, while creating their bridges, is to have them build a drinking straw bridge that can support some weight, such as a cup of pennies or some paper weights.
Put four drinking straws side-by-side and attach them to each other using a three sewing pins throughout the length of the pin. If the sewing pins are not long enough to go through all four straws, remove one of the straws. Repeat this step one more time so that you have two sets of three to four drinking straws.
Put the two sets of drinking straws side-by-side and insert three pins through the centre straws. Try to get at least three or four of the straws in the middle hooked with the pins. To put the pins in, you'll have to bend the outer straws out of the way; try to not bend them too much so that they don't break. You should now have a bridge deck that is six to eight straws in width.
Put a straw at a 90-degree angle at one corner of the deck. Attach it to the deck using a sewing pin. Place a second straw at a 45-degree angle from the first straw, in toward the deck, and attach it to the top of the first straw, and also to the deck, using two pins. This will make a pillar with something that resembles a suspension cable made of straws. Repeat this step until you have at least four of these pillars on each side of the deck.
Place the drinking straw bridge so that is spans a gap between two desks or two table tops and place the weights on the bridge. Add more weight until you see that the bridge starts to bend.