Operational definition is a statement that shows the "what you do and what you observe".
For example, the operational definition for coagulation of latex:
The "what you do" is... when acid is added to latex..
The "what you observe " is.... white solid is formed.
Therefore the operational definition for the coagulation of latex is ..When acid is added to latex, white solid is formed. (SPM 2008)
The operational definition for the neutralisation of acid or alkali could be... When acid is added to alkali with a few drops of phenolphthalein, the pink solution changes to colourless.
The operational definition for the reactivity of Group 1 elements towards water:
When a metal which is lower down in Group 1is put into a basin filled with water, the movement of the metal on the water surface is faster // more vigorous// the flame produced is bigger or brighter.
Teacher Norini hopes that you girls and boys have some idea now the meaning of operational definition. Well, you can always ask Teacher Norini if you don't.