Bridge Building is Fun!

Y4 Ben Thomas

Benedict House School in Sidcup held an inter-house civil engineering challenge on 21st May. All the children at the school are in one of three houses named after great seafarers and explorers – Nelson, Cook and Scott.  Competitions are held between the houses throughout the year . For the engineering challenge each class from Years 3-6 was divided into house teams and challenged to build the strongest and most attractive bridge they could with the materials provided.

Each team was given a zip-lock wallet containing 4 cardboard tubes; 4 paper sticks 8″ long and 4 more 4″ long; 2 sheets A3 paper; a pack of pre-cut sticky tape; 2 metres of string; 10 paperclips; a pair of scissors; a one hole punch; a set of felt tipped pens, a 12″ ruler and an AO sized sheet of corrugated cardboard. The teams had to build a bridge on special wooden platforms with a gap between the supports, called abutments, of 30cm. A river was painted on the base of the platform.  No part of the bridge could touch the “river” between the abutments or pass beneath the bridge platform.

Points were awarded out of five for team working, the appearance of the bridge and engineering principles. Weights were added to each bridge until it collapsed or touched the “river” between the abutments. The maximum weight in kilograms was doubled and added to the other scores. As each bridge was tested, the group was encouraged to suggest ways that the design could have been improved. In this type of activity there is as much to learn from “failure” in an engineering sense as from the process of construction.

Bridge Testing

It was particularly impressive to see the way the teams worked together and the children encouraged each other through the testing phase, regardless of which house they represented.

The weights carried by the bridges increased through the age groups with the average weight for Year 3 being 1.5kg; Year 4 around 2.5kg; and Year 5 around 4.0kg. The most impressive results were from Year 6 with the weights achieved ranging from 4.5kg to an incredible 11.5kg.  The overall competition was won by Scott house and special certificates were awarded for strong team work and sound construction skills.

The best design made excellent use of three engineering principles:

  • string was used across the span beneath the bridge deck and tensioned using paper sticks in the holes in the abutments secured by paperclips;
  • the cardboard tubes were used to extend the abutments and reduce the length of the span;
  • every piece of the large cardboard sheet was used, creating a deep deck with maximum stiffness to resist the load from the weights.

Overall the event was a great success with really positive feedback from the participating children and their parents and teachers.

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