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Tufts OpenCourseware
Author: Fulcrum Institute Development Team

Snapshot: Investigating Acids and Bases

Ms P’s Goal: Students will understand what pH is, including that pH is a property of liquids, including common household substances, acids have pH lower than 7.0 - the stronger the acid, the lower the pH, neutral substances have pH 7.0, and bases have pH higher than 7.0 - the higher the pH, the stronger the base.

Snapshot: Ms P’s students have used pH paper to test over 50 household substances and recorded their results on a class chart. Before they collected data, they predicted that most common household substances would be either neutral or, if they were acids and bases, they would be weak. They reasoned that strong acids or bases could be harmful and so you wouldn’t expect them to be readily available. As they wrap up their study of acids and bases, Ms P asks her students to write a final report that explains the purpose of their investigation, what they did, what they found out, and what they learned about the acid/base properties of common household substances.

The class, brainstorms characteristics of a good report about their investigations. They decide that reports should include the investigation question, a clear description of the procedure, an easy-to-read table or chart that shows the results, a summary of what they found that is supported by data from their tests, and how the results compared with their predictions. Ms P posts the list of criteria so it’s visible to students as they write their reports. After they write draft reports, they share the drafts with peers and receive feedback. Ms P notices students are using the class list of characteristics of a good report to organize their feedback. She plans to read the drafts at home in the evening and add her feedback.

Tomorrow, based on these drafts, she plans to identify areas of the reports that were not as well-developed as others. She hopes she will find examples among these drafts that she can use as strong models for each part of the report. Then, she will provide time for students to refine their final reports.