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Lesson 3-4: The Water Molecule and Dissolving Part II

Page history last edited by mariaelizabethbunn@... 5 years, 10 months ago



Engaging the Student (Entry Task) 

Developing the Ideas--Lesson

Checking for Understanding (exit ticket)

Student Handout 
Teacher/Lesson Notes

2-3 class periods

  1. Conduct the demonstrations provided in the lesson plan to show that different substances have different solubilities.
  2. Discuss the results of the demos & introduce the investigative question for each activity. (Questions to ask students are in the lesson plan). 



View the full lesson plan here:


Answer Key to Student Activity Sheet here:



  • Students will observe a solubility test between salt and sugar. They will then be presented with four known crystals and an unknown. Based on the solubility demonstration, the class will design a solubility test to discover the identity of the unknown.



  • Students will be able to identify and control variables when designing a solubility test.
  • Students will be able to explain why different substances dissolve to different extents in water.


Materials for the Demonstrations

  • Gram balance
  • Simple balance
  • Graduated cylinder
  • Water
  • 4 clear plastic cups
  • 2 small plastic cups
  • Salt
  • Sugar
  • Cereal balls (Kix work well)
  • Zip-closing plastic bag (quart-size, storage-grade)


Materials for Each Group

  • Salt (sodium chloride)
  • Epsom salt (magnesium sulfate)
  • MSG (monosodium glutamate)
  • Sugar (sucrose)
  • Coarse kosher salt (sodium chloride)
  • Water
  • Black construction paper
  • Masking tape
  • Pen or permanent marker
  • Magnifier
  • Gram balance
  • 5 small plastic cups
  • 5 clear plastic cups
  • Graduated cylinder
  • Paper towel


Links to images & animations used in the lesson:





Exit Ticket:

  • Describe the crystals in each cup. What do you think is the identity of the unknown?


Students should discuss the shape and size of the different crystals and notice that both salt and the unknown look very similar.


Tell students that the unknown is coarse kosher salt. It is chemically the same as regular salt, but the process for making ordinary table salt and kosher salt is different and this is why they look different.



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