Mixtures & Solutions
Investigation 2
Part 3
Saturation Puzzle
The students will be repeating the same procedures followed in Investigation 2, Parts 1 and 2. Students receive an unknown (Epsom salts), saturate 50ml of water, and using the property of mass, determine the saturation point. They identify the substance by comparing their results to a table of known saturation points.
3. Lesson set up and Management
Properties of Substances (PR01 1.1.1)
• Use properties to sort natural and manufactured materials and objects, for example, size, weight, shape, color, texture, and hardness. Grades K, 1, 2, 3, 4, & 5.
• Use physical and chemical properties to identify and describe substances; for example: density, boiling point, and solubility. Grades 6, 7, & 8.
Structure of Systems ( ST01, STI02, STI03, & STI04 )
• Know that matter is made of small particles called atoms and molecules. Grades K, 1, 2, 3, 4, & 5. (ST01 1.2.3)
• Understand that all matter is made up of atoms, which may be combined in various kinds, ways, and numbers to make molecules of different substances. Grades 6, 7, & 8. (ST01 1.2.3)
Changes in Systems (CH01 1.3.3)
• Know that matter can undergo changes of state such as evaporation, condensation, or freezing and thawing. Grades K, 1, 2, 3, 4, & 5.
• Understand physical and chemical changes at the particle level and know that matter is conserved. Grades 6, 7, & 8.
Designing Solutions ( DE02 & DE03 )
• Propose, design, and test a solution to a problem. Grades K, 1, 2, 3, 4, & 5. (DE02 3.1.2)
• Identify, design, and test alternative solutions to a challenge or problem. Grades 6, 7, & 8. (DE02 3.1.2)
• Evaluate how well a design or a product solves a problem. . Grades K, 1, 2, 3, 4, & 5. (DE03 3.1.3)
• Compare and contrast multiple solutions to a problem or challenge. Grades 6, 7, & 8. (DE03 3.1.3)
Solubility is different for different materials, and can change with temperature and different solvents. ( This is the concept in the book. However, if you do the crystal growing experiment in the reading book, you never use different temperatures or solvents in any of these investigations. )
3. Lesson set up and Management
Materials:
If you did not make a handout packet, copy Handout # 10.
Set up a water station and an unknown chemical station with 25ml spoons.
Check the student tubs to be sure they have all the materials listed. The mass set can be the small cubes from a Base Ten Kit as they are 1 gram cubes. If your school has the Measurement Kit , there are gram cubes in this kit.
Student Management:
The opening discussion in the teacher's manual is not the best opener. As a safety precaution, students should be taught not to mix materials in a solvent without some idea of what the materials are. Instead, tell the students that you know what material they are using, and you want them to design an investigation that will help them figure out what it is. Ask each group to take out their journals or a piece of paper, and design their investigation, including a materials list and step- by- step procedure. You need to check each investigation design before the groups may start. Make sure students include separation by evaporation in their procedure.
The investigation design portion can be done in one session, and the actual investigation can be done on another day.
I do not hand out the Chemical Data Sheet, Handout #10, until the students have finished the mixing portion and feel they have reached saturation (students often look at the sheet and stop too early, thinking they have already figured out what the material is). At this point, the students are given Handout #10 and told to fill out the bottom portion, including identifying the material they think they have.
This portion of Investigation 2 is an ideal time to assess the students understanding of the concepts of solubility, separation and the use of a material's properties to identify the material. The rubric in the assessment section, on page 9, is very helpful. Save 2 of the evaporation trays with the crystals for lesson 4.
Writing Support:
This is a good time to use a writer's workshop to introduce how to write a procedure as a type of expository writing.
Write the questions on page 25 of Investigation 2, Part 3 on the board and have the students write answers in their journals as explanations.
Reading Support:
There is no specific reading for this lesson.