Skip to main content

Salt and Sugar on the Sidewalk

Salt, sugar, limestone, and plastic particles affect the pattern of evaporation on a sidewalk. 

Farley, Iowa, Dubuque County

Possible Guiding, Compelling and/or Anchoring Questions

  • What forces are involved? Why is the water around the particles evaporating at a different rate?
  • Why did the phenomenon occur with some particles but not the others?

Classroom Suggestions

  • Compare which of the substances dissolve in water or other liquids (like dissolves like) and tie to chemical bond types. 
  • Compare sodium chloride and calcium chloride’s attraction for water and link to road deicers. 
  • Topics to extend the discussion: How do salt and sugar affect whether foods lose moisture and get stale? (Note: stale crackers are not dry enough; stale bread is too dry.)
  • Evaporation rates in salt lakes decrease during drought periods (per surface area) as previous evaporation concentrates the dissolved salt.

Related Resources

Iowa Core Alignment

Physical Science
High School (9-12)
Disciplinary Core Idea
PS1: Matter and Its Interactions

Credit Info

Submitted by Diane May


Have you used this resource in your classroom? Do you have ideas for improvement? Share your ideas, experiences and feedback about this phenomena.

REAPCorporation for Public BroadcastingAlliant Energy