A good demo in class is just as effective as a well planned out lab activity. Density is such an important concept that is applied to so many different topics in science. Sometimes the math (d=m/v) doesn't sink in with students when it comes to density. Try a demo to SHOW them how it works! Most students can recognize Coke and Diet Coke as a soft drink. This is an easy and effective way to show how density works by just comparing the 2 of them in water. Before placing them in water, it's really important to have students make a hypothesis as to what they think is going to happen. Have them explain WHY!!! Once that class discussion has completed, simply place them in water and make and observation as one will float and one will sink. It's all about the sugar content!! Have fun with this one as the kids will be amazed!!!