ASTM C1161 specifies a procedural overview for the bend testing of ceramics.
Specimens are usually a flat plate.
A 3 point or 4 point bend testing fixture can be used, depending on how the material behaves. Four point test jigs tend to be easier to set up and they apply an even load across the sample.
Flexural Strength is given by the maximum stress that the sample can withstand before snapping. Ceramics tend to be brittle materials so it is very rare when the test does not result in a fracture failure. Flexural Modulus can also be dervied from the stress/strain data.