Mineral Reserves

1. After obtaining the items outlined in the Materials list, assemble the boxes students will use to determine the volume of aggregate (sand) above the bedrock.
2. Place plaster cloth sheets in your box to simulate a rolling, undulating surface. This represents the surface of solid bedrock. Use wadded paper or other materials to create an irregularly shaped contour. Use duct tape to close openings between plaster cloth and box sides; this will eliminate the loss of sand when calculating the volume of sand in the box. Be sure to vary the topography of the bedrock to make it challenging for your students.
3. Have students fill the boxes with sand and spread a level surface approximately 2”–3″ below the box top. Once that is completed, have groups trade boxes. 
4. Ask students to calculate the volume of aggregate (sand) in the box above the bedrock. Inform students that they cannot take the sand out to measure its true volume until the very end.
5. To calculate the volume, have groups “drill” five holes throughout their territory and measure the depth of each drill hole. Inform students that they may use straws or a ruler to drill, mark, and measure where they drill.  Have students create a diagram, like a map, and mark the locations of the drill holes. Ask students to consider why they are choosing these locations. Lead a class discussion about how groups will use their measurements to calculate a volume.
6. Have students “drill” into their chosen drill sites and record the measured depth at each location. Students should use the strategy they decided on in the previous step to calculate the volume of aggregate. Once students have “estimated” as closely as possible using their system of measuring volume, have them measure the actual volume using large beakers or measuring cups.
7. Ask students to use the following equation to calculate the accuracy of their results. 

Percent error = [your value – actual value] X 100 Actual value

8. Use the Guiding Questions to lead a class discussion about outcomes.

Figure 1. Box without the sand. Note the irregular bottom surface of the empty box.

Figure 2. Box with the sand added and five straws used to estimate the volume of sand in the box.

1. What were their sources of error?
2. What would they do differently to decrease the percent error?
3. Would a different “drill pattern” give more accurate results?
4. Would more “drill holes” have helped?
5. In the real world each “drill hole” costs money, so how many more could you afford?

Next Generation Science Standards

Science and engineering practice—Developing and using models, Using mathematics and computational thinking

Crosscutting Concepts—Systems and system models 

Disciplinary Core Ideas—Natural Resources 

©Minerals Education Coalition 2022