1. Define Density and explain how it is calculated.
2. Calculate one variable in Density = mass / volume (D = m/v) when given the other two variables.
A neat example of density changes is a lava lamp -- it's not very expensive and it's a dynamic example of the concept. (I used to have one in my classroom, but... it got stolen-- so store your stuff away!)
Here's a video discussing the concept and showing a few problems. (there is a small inconsistency in Problem #1)
For your information, from D = m / v:
v x D = (m / v) x v --> v x D = m
(v x D) / D = m / D --> V = m / D
I point out to my students that all three formulas are in "D = m/v" , it just needs to be rearranged algebraically.
Here is another video showing Density examples using a Factor-Label approach:
Here are some worksheets for your class:
The following worksheet might print out a little faded, but I like the variety of questions:
During this beginning month of Chemistry class, many Density labs can be performed safely -- this gives time to learn about chemical and fire safety and get lab safety contracts signed.
Here is a quick review of reading a graduated cylinder:
Once objects are collected for these labs, you could use them the next year. Check in your Science Department to see if there's already a collection of objects used for Density labs.
The 2nd method in the lab is for irregularly-shaped objects -- the method of Water Displacement is to be demonstrated by the teacher. This video provides a reminder of this technique -- it's not concerned about Significant Figures -- you can measure to one decimal place with the graduate cylinder used:
A graph of the data collected is required in the data analysis. If you want to graph by hand, here is a link to blank graph papers for your use:
I recommend drawing the points and line for one liquid before moving to the next liquid. Use a symbol around the points to differentiate the lines for the three substances (for example, circle, square, triangle). Include a Key on the graph to identify the line symbols.
Here's an online graphing program:
And a sample version of Graphical Analysis is available:
Check in your Science and Math Departments to see if your school owns a graphing program.
One more simple lab dealing with Density and the importance of Significant Figures is "Thickness of Aluminum Foil" . It's interesting to collect the class results, maybe on the board. With those values, you can discuss the consistency of the results.