I created this lesson for my 8th grade physical science students. This lesson is an excellent example of how the density of a substance does not change when the size of the substance changes. Students will measure the mass and volume of a bar of chocolate and then use the density formula to find the density of the chocolate bar. Then the students break the chocolate bar in half, re-measure and re-weigh the chocolate bar and then find the density of the chocolate bar again. The students repeat and break the chocolate bar into 1/4. Students should see that no matter the size of the chocolate bar the density is the same.