Lesson Summary In this part of the investigation, students gather more evidence for the presence or absence of calcite.  After the rocks have soaked in the vials of vinegar overnight, students pour off the liquid into evaporation dishes.  The vinegar evaporates over 1 or 2 days, then the children can look for calcite crystal formations left in the evaporation dish.  They will compare evaporating dishes with the various rock and vinegar residue to a control dish of calcite in vinegar residue (crystals) and a control dish of just vinegar. Teacher Background This is a good opportunity to have students recall about solids dissolving in liquids and the fact that only liquids evaporate, leaving behind the solids.  Like water, the vinegar will evaporate into the air.  Calcite crystals have a very distinctive shape, much like frost on a window.  Students have also described the appearance being somewhat like fur.  A frothy white crystal is also usually apparent.  The dishes that will show calcite crystals are the samples that contained limestone and marble.  This is especially intriguing when one notes that limestone is a metamorphic rock, which turns into marble over a long time, given the proper conditions.  There is a page in the back of the Science Stories that shows metamorphic rocks.  Set-up/Management Tip The evaporation process may take more than one day.  It is wise to plan another activity in case the evaporation is not complete.  This would also be a good opportunity to have the students read related non-fiction texts or do a class Read-Aloud. Literacy Support Books Available Through VAST Mediagraphies: (see Literacy Links) Science Stories “The Two Boys: An Aborigine Story from Australia” Word Wall/Word Bank The following words are key vocabulary words that will be introduced in this lesson and reinforced throughout the unit: evidence