This worksheet allows students to see the Law of Conservation of Mass in action. Objects made up of various shapes are given on the left side of the page along with their total mass. The objects are broken up into their composite shapes on the right side of the page and students must fill in the missing masses. Some of the missing masses are the sum of each individual shape, showing that the total mass when the shapes are attached is equal to the sum of the masses of each shape. Some of the missing masses are for one individual shape. By finding the total of the other shapes and subtracting from the total given for the figure, students can solve for the mass of the missing shape. Answer key included. Created by Amber Mealey.