Chair Building

I use this lesson plan as an activity in the Grade 7 Science Structure and Forces unit. The students work in pairs.

• Students draw a plan for the chair design.
• Concepts to Include might include corrugation, lamination, and triangulation; design considerations such as arches, beams, trusses, and columns; and show an understanding of what fastening techniques for this design i.e. friction fit, mass, and glue, staples, rope, tape (within reason), or nails or screws (within reason).
•  Consider properties i.e. stability, brittleness, ductility, hardness, plasticity, compression, and tensile strength.  Students need to consider deformation, structural stress, structural fatigue, and possible structural failure. What are internal forces (mass of materials) and external forces (load on the chair).
• What role do aesthetics play i.e. symmetry and appearance? What is the chair used for?
• Students use recycled material i.e. cans, plastic containers, and cardboard (boxes, tubing, and pieces).
• Students construct and track changes. The original chair design might be altered depending on material availability, functionality, and durability.  They should test the chair as they build.
• I limit class time to 2-3 classes. Most materials are found at home and students can receive help from family, friends, or neighbours.
• I email parents and tell them they are consultants, who can offer expertise, guidance, and time unavailable in the classroom. Parents are good about insuring students do the lion’s share.

Students are innovative. One student included pop bottle (he told me it was for pop) holders in the arms of a deck chair. Another student gathered discarded pizza boxes after hot lunch and used those.

Assessment is a rubric. A criterion is I test the chair. Its ability to hold my 250 pounds, give or take, is part of the challenge. Only one chair collapsed under my mass. It lacked support.

This is a Grade 7 project, but I think other can modify it for other grade level needs. Students can work in pairs.

Cautionary note: I allow nails, screws, and tape as fasteners, but within reason. The first time I did this activity a student built a nail chair. He used so many nails it is doubtful they were recycled.

Here are some examples of this year’s chairs.

This chair is made from used pressure treated lumber and plywood. The back folds forward and the student used baling twine he got from the farm as the hinges.

This chair is constructed from willow. The willow qualified as recyclable as the students were going to have to dispose of the willows when they cleared underbrush anyway. The only thing missing is a cushion. These students could go into business selling yard furniture.

Although this stool did not have triangles for stability, the centre piece helped in that respect. When I sat on the stool, it was wobbly, but with my mass it became less so. The students used baling twine as the only fasteners. One of them has horses and these were available.

This chair is built from recycled wood and a discarded cushion. The students gathered the wood from the neighbourhood and a neighbour helped. He drilled tap holes for the screws.