Lesson Summary Students learn about what hardness is and how to test for it.  They are then challenged to identify minerals by their hardness.  Students use 3 tools to test for hardness (fingernail, penny, and paperclip). Teacher Background A relatively “soft” mineral can be scratched by the “softest” tool (the fingernail), while the hardest minerals cannot be any of the three tools provided.  Any mineral that can be scratched by the fingernail can of course be scratched by  the other 2 tools.  Conversely, a very hard mineral that cannot be scratched by the hardest tool (paperclip) should not show scratches from the fingernail or penny.  Students need to be encouraged to really check to make sure they can FEEL a scratch.  Sometimes a mark can look like a scratch but can be rubbed away, therefore, it is not a true scratch.  Mohs’ Hardness Scale is used by real geologists to identify and compare minerals.  More information is given about quartz, fluorite, calcite, and gypsum used in this investigation in the Teacher Guide.  Calcite is used again in Investigation 3, and both calcite and quartz are used in Investigation 4: part 1. Set-up/Management Tip Be sure to review properties of each mineral (named #1, #2, etc. at this point), so each group has them placed properly.  Review safety and common sense with the children about using paperclips. The children are usually very interested in learning about their own birthstones.  This is a good place in the unit to do Internet research. Literacy Support Books Available Through VAST Mediagraphies: (see Literacy Links) Science Stories Selection(s) “Digging It Up: Mining for Minerals” “Birthstones” Word Wall/Word Bank The following words are key vocabulary words that will be introduced in this lesson and reinforced throughout the unit: quartz gypsum calcite fluorite