Acid Rain Lesson Plan
Activity 1 – the pH Scale
Time: 1 Hour
At the end of this lesson the student will be able to:
- Describe the pH scale and its components
- Explain why a pH measurement must be accurate and why small changes in pH are important.
You will need enough of the following for each student:
- Dried apricots
- Grapefruit pieces
- Lemon pieces
- Writing paper, pencils
- Four paper cups for each child
Instructions to Teacher
- Write on blackboard:
- Molasses - pH 5
- Dried Apricots - pH 4
- Grapefruit - pH 3
- Lemon- pH 2
(Other common substances' pH can be found in Table 1)
Instructions to Students
- Sample each item. You may try any one of the four samples first.
- Record which sample tasted the least bitter, the most bitter. Rank them in that order. Save these answers for the discussion later.
Questions to Students
- How did you rank the four samples, least bitter to most bitter?
- Why did you rank them this way?
- Where do you think the following fruits and vegetables would be placed on the pH scale: Apples? Carrots? Spinach? Jams? (pH 3, 5, 5, 4, respectively)