Introduction to pinhole astronomy
  The observation of the Sun with a pinhole in order to check the first and the second Kepler's law has been realized for high school students. The settling of the experiment in order to minimize the errors of measure has permitted to verify the Rayleigh formula for obtaining sharpest images given the diameter of the pinhole. 
Costantino Sigismondi
astro-ph.IM physics.ed-ph