We will make the indicator by soaking a paper in a solution of CoCl2.6H2O and allowed it to dry. Thetheory is that on a humid day, with Le Chatelier’s Principle in effect, water from the humid air adsorbson the paper and pushes the equilibrium to the left changing the color from blue to pink. On the dryday, there is less H2O and the equilibrium is pushed to the right making the paper blue. Temper aturehas a small effect too.