Ask students to include the following information in their lab reports:
Definitions: The definitions of "clear" and "opaque" in their own words.
Equipment: A list of equipment and materials they used in the experiment.
Process: A step-by-step description of the experiment.
Observations: Label two separate columns a "opaque" and "clear." Ask students to categorize the different physical states of the substance depending on their opacity or clarity.
Predictions: Students should write whether they predict the substance will be clear or opaque in its different states.
Hypothesis: Their thoughts as to what factors could make a substance appear opaque or clear.
Other: Any questions or notes that arise in the course of the experiment.
Show the students an individual, granulated white sugar crystal. Next, pour a small pile of sugar on a plate. Ask them to compare the different states.
Tell the students to place a small pinch of sugar on a separate plate. Instruct them to crush the sugar with the back of a spoon until it becomes a fine powder. Ask them to consider the reasons why many small crystals are opaque, but a single, larger crystal is clear.
Ask students to stir a tablespoon of granulated white sugar into a cup of warm water until they dissolve completely. Students should watch the crystals gradually shrink and note whether individual crystals appear more opaque or transparent as they dissolve.
Students should then consider that the sugar crystals dissolved in the water are smaller than the sugar crystals they crushed, but became transparent rather than opaque. Ask them write down notes on what role the size of the crystal has on its clarity.
Ask students to use a pair of tweezers to place a few powdered sugar crystals on a slide. Ask them to examine the crystals under the microscope and to note any differences in their lab report. They should also consider why they can't see through the crystals with their eyes alone.
Make sure the sugar water has cooled down so that it won't fog up the slides. Ask them to use a pipette to place a 1-millimeter drop of sugar water on a different slide and to cover it with a slide cover. They should observe this slide at the highest possible magnification before writing down their results to ensure it is still transparent.
Discuss the results of the experiment with them. Ask them to write a hypothesis that takes into account the size of the sugar crystals and the limitations of the naked eye.