Sofia and Marcus investigate the exothermic reaction between magnesium ribbon and hydrochloric acid. They do an experiment to test this hypothesis:
" The greater the mass of magnesium ribbon, the greater the temperature increase. "
Before Sofia and Marcus do their experiment, they try using different masses of magnesium ribbon and different volumes of hydrochloric acid, to check that they can measure the temperature change.
Question: - What do we call this work that you do, before starting the main experiment?