Lesson Plan

Red, Yellow, Green - More Than Just Traffic Lights

#STEMChallenge Investigate acids and bases and the pH scale
Donna M.
Classroom teacher
Vista Visions Academy
Vista, CA
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My Grades 6, 7, 8, 9, 10, 11, 12
My Subjects Science, Health & Wellness
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Students will be able to observe color changes in chemcial reactions.

Students will be able to reason how to change a solution to attain the desired color with universal indicator.

Students will be able to identify the pH of a solution.

Students wil be able to accurately record procedures and observations.

Students will be able to communicate results. 

All Notes
Teacher Notes
Student Notes

1 Hook

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Use the lesson plan from the the video, "Ideas in Chemistry," from the Teaching Channel.  https://www.teachingchannel.org/videos/hs-chemistry-lesson-demonstrations

The lesson begins with a demonstration of the teacher pouring a purple-black liquid (potassium permanganate) into four glasses that each contain various chemicals. Students observe color and texture changes and hypothesize what is causing the color change. Either do a similar demonstration or show that portion of the video.

2 Direct Instruction

Review the characteristics of acids, bases and the pH scale. This may be done through a presentation, textbook reading or using a simulation such as the ExploreLearning Gizmo: pH Analysis. To observe what is happening at the molecular leves, use Chem4Kids: Acids/Bases I and Acids/Bases II. Stress that the pH scale is a continuum and as a solution becomes more acidic or basic, the color moves up or down on hte pH scale.

3 Guided Practice

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Follow the lesson plan presented in "Ideas for Chemistry." Use the "Indicators in Chemistry Presentation" and the "Results Table Sheet," at the bottom of the page. Make available acids, bases and universal indicator for students to use, along with the appropriate labware. Have students work in groups to explore and observe what happens when they mix universal indicator with different chemicals.

4 Independent Practice

Activity: Creating

Continue with the lesson plan as students work to meet the challenge of creating a red, yellow and green solution. Students should use the "Results Table Sheet," to record their observations and trials. Stress that record keeping is extremely important so results can be reproducible.

5 Wrap-up

Activity: Presenting

Student groups present their findings. If there is a major discrepancy regarding how to create a color, the group in question should repeat their experiment and revise their results in necessary