The chair seen opposite has been badly designed for a young child. The child is perched on the edge of the seat with his legs dangling over the edge. His back is not supported. This is an example of bad ergonomic design.

It is extremely important that products like chairs are designed with ergonomics in mind. The chair should be comfortable for the child, supporting his back and allowing his feet to touch the floor.

The chair opposite has been well designed:

The chair is comfortable.
The back rest supports the child’s lower back.
His feet can touch the ground allowing him to help support his own weight.
The size of the seat means that he can both touch the ground with his feet and support his back against the rest.

ERGONOMICS EXERCISE

A: The measurement from the ground to the lower back.
B: The distance from the ground to a comfortable seating position.
C: Seat distance - calculated to allow the child’s legs to hang correctly over the edge and his lower back to be supported by the seat rest.

Exercise: Select twelve people at random from your class. Collect the measurements A, B and C and work out the average for each one.

If you were to design and make a chair for pupils of your age you would be wise to base the dimensions of the chair on the measurements you have just calculated.

Draw a basic diagram of a person sat at a picnic table. Identify the most important measurements that need to be calculated in order to design and make an ergonomically designed picnic table.

Check the average measurements you have calculated against the dimension of a normal classroom or kitchen table. How do they match?

The table below is a sample. It shows measurements A, B and C arranged in table form with the average for each worked out. The average measurements are then used to help design and make an chair that has been based on sound ergonomic factors.

The diagram below shows a picnicker ready to eat his lunch. Add three important ergonomic measurements that must be calculated if the table is to be ergonomically designed. These measurements can be called A, B and C.

Explain why each of these measurements are important.

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