In a chemical equation, the arrow points away from the reactants and toward the products. In the following analogies, the relationship between the words on each side of the double colon (::) is similar or the same.

reactants : products :: input : output
reactants : products :: start : finish
reactants : products :: before : after

Interactive exercise. Assistance may be required. Drag the boxes to the reactants and the circles to the products.

Interactive exercise. Assistance may be required. Click through the following presentation.