An elementary formalism for general relativity, Andrea A. diSessa, Am. J. Phys. 49(5), May 1981
An elementary formalism for representing curved space-time is developed which allows transparent qualitative explanation of such general relativistic effects as gravitational redshift, deflection of starlight, and the precession of a gyroscope in orbit. The formalism is based on a method of surveying and subsequent mapmaking and does not rely on the usual tensor machinery, connection coefficients used to calculate the magnitudes of those relativistic effects and even build a simple computer simulation. In addition, the formalism is used to make a conceptual analysis of Einstein's principle of equivalence which explains the famous factor of two missing from his first calculation of the deflection of starlight using only the equivalence principle. A final section outlines a number of student activities.