The Welding Institute, based in Cambridge, visited St John’s as part of Form 3’s ‘Wonder Afternoon’. The children discovered that welding with chocolate is an innovative and fun way of demonstrating welding and engineering principles. Bridges are made of all kinds of materials; stone, steel, concrete, wood and, in this workshop, chocolate!
Each group had the challenge to see if they could engineer a chocolate bridge strong enough to withstand increasing amounts of weights. A simple bridge was made using one plank that spanned the distance to be crossed. The children worked collaboratively to melt the sides of the chocolate to make a ‘v’ shape. They then stuck two ‘v’ shapes together to make a cuboid box girder. Intense collaboration within groups followed as the children estimated how much weight the box girder bridge could withstand compared with the simple plank. The children realised that a box girder bridge is made from a long beam and that the box shape makes it stiffer.
Questions were asked, such as, ‘If and when the bridge breaks, how does it break?’ and ‘Why is your chocolate box girder bridge stronger?’ One Form 3 explained, “We discovered that a single bar of chocolate could not hold as many weights as the constructed chocolate rectangle bridge which held 4.5kg. It was a great experience to discover how the structure of bridges can make them stronger.”