[Free Registration/Login may be required to access all resource tools.] In the following online tutorial students will identify three methods for measuring the amount of matter in a sample. They will define the mole and its relationship to Avogadro's number and they will use Avogadro's number to convert between moles and the number of representative particles of a substance. Students will also relate the atomic mass of an element to its molar mass and calculate the molar mass of a given compound.