Math,Science and Technology

Which form is stronger?

Explore with a sheet of paper the strength of accordion-pleated sheets compared to simple folded sheets.

Materials:

• Two identical sheets of paper
• Pennies
• Notebook

Fold one sheet accordion-fashion along its length and make a bridge between two books.

Fold the other in half lengthwise, then again in half lengthwise. Be sure the two papers are the same length. Make this paper bridge two books.

Working in pairs, have one student add pennies one by one to the bridges; have the other student record the number of pennies added before the bridges collapse. Which folded shape is stronger?

Bridges good enough to eat!

Have the students construct bridges of pasta to span 30 centimetres. Remind them that this will mean the bridge has to be longer than 30 centimetres. If the class is old enough, emphasize triangles as being very stable shapes. Suggest that they look at pictures of bridges to see how the triangles fit together. Have a contest to find the strongest bridge, if the children do not mind having their bridge broken.

Shifting Shapes

Distribute 10 toothpicks to each student. Ask them to create triangles with three toothpicks, squares with four, pentagons (5), etc., working through hexagon (6), octagon (8), to decagon (10). Have them count the number of sides and the number of angles in each shape as they go. What happens to the size of the angles as the number of sides increases? With more toothpicks, have them try making triangles in the larger shapes.

Self and Society

Visit a bridge near your school. Discuss what the cars, trucks and pedestrians would have to do if the bridge were not there. What shape is the bridge? What does it cross over? Of what material is it made? When the children return to school, have them draw the bridge from memory, or have the class create a river mural with many bridges.

Language

Discuss with the children the different types of bridges and the different parts of a bridge:

arch
curved structure, support for bridge, roof or floor

beam
long piece of squared timber or of metal, supported at both ends

cantilever
beam or girder fixed at only one end

span
the stretch from side to side, or end to end

pier
support of arch or of span of bridge

girder
structure or beam of steel forming span of bridge

truss
supporting framework of bridge, often formed of triangular braces

suspension bridge
roadway is hung across river on wire or chain cables passing over towers and anchored, without support from below

trestle bridge
bridge supported with open braced framework of wood or metal or concrete

Ask the children to name all the materials that they have seen in a bridge: wood, steel, concrete, stone.

Talk about bridges that open: swing bridges, drawbridges and lift bridges. Discuss the obstacles bridges cross: rivers, roads, ravines.

Discuss the difference between a bridge and a dam; a tunnel; a causeway; a viaduct*; an aqueduct*.

*Viaduct: a series of arches making a long, bridge-like structure.

*Aqueduct: a series of connecting bridges topped with a trough to carry water across a valley.

The Three Billy Goats Gruff

Primary children may enjoy this activity. Read this wonderful tale about crossing a bridge to your students. The original author was Peter Christen Asbjornsen, but the tale has been retold by

Rounds, Glen. The Three Billy Goats Gruff. New York: Holiday House, 1993.

The Arts

London Bridge

For primary students, teach the class "London Bridge is Falling Down," and play it as a singing game, two children making the arch, the rest filing through. When all are through the arch, the first two children through the original arch make a new arch.

The words can be found on the activity sheet, London Bridge

Magic Arches

Using plaster-filled bandage (rolls of this are obtainable in medical supply stores), hang loops from the ceiling or doorway. Using a plant sprinkler, spray loops with water. If appropriate, let the students do the spraying. Let loops dry, then turn them upside down for beautiful structural arches that can support weight!

Go back to Structures and Shapes

Questions about school programs should be sent to scorbeil@technomuses.ca.