Mozambican Techniques for Laying Out a Rectangle

How would you lay out the foundation for a shed? The Western definition of a rectangle as a four sided figure with right angles requires using a preconstructed right angle, such as a carpenter’s t-square, or creating a right angle using a 3-4-5 right triangle. By the Pythagorean theorem a triangle with lengths of sides in the ratios of 3-4-5 must be a right triangle.

However, the people of Mozambic use a different approach to constructing a rectangle. Their methods are based on a defnition of a rectangle as a four sided figure with opposites of equal length and having equal length diagonals. The following illustrates two ways to use this apporach.

Mozambican Method 1.	Mozambican Method 2.
Start with four sticks the size of the desired sides.	Start with two equal length ropes tied together at their midpoints.
Lay them out to form a four-sided figure	Lay out the width desired. Stake down two ends of the ropes.
Using a rope to measure the diagonals adjust the figure until the diagonals are equal.	Stretch out the ropes and stake down the other ends.

Reference

• Gerdes, P. (1988). On Culture, Geometrical Thinking and Mathematics Education. Educational Studies in Mathematics, 19, 137-162.

Ethnomathematics Snapshots [Previous Snapshot | Contents | Next Snapshot]