Resonant cavity perturbation as a means to measuring permittivity has been used since the early 1940s. It is attractive because it is non-contact, non-destructive and experimentally simple. Only recently, however, has the cost of a small analyser board become acceptably low that experiments can be carried out in schools and colleges. Using the TE 1,0,1 cavity mode in a rectangular cavity, measurements of permittivity for distilled water, methanol and PTFE in the microwave region of 1 GHz are presented and these agree well with published data. A granular sugar sample is also investigated to confirm measurements carried out with a compact Lecher Line apparatus.