Begins with corn starch. Mixed cold, it forms a coarse suspension that clears by filtering or settling. When boiled it forms both a cloudy colloidal suspension and a clear true solution. Apply concepts and vocabulary learned here to a series of tasks that clean muddy water: Alum coagulates the clay, chlorination bleaches all traces of food coloring, but only distillation makes it pure. Use common salts to study about crystals, concentration and saturation, rates of dissolving and limits of solubility.