pH - Flipped (Day 2)

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Objective

SWBAT list the pH of every day household items by conducting pH testing using cabbage juice.

Big Idea

In this lesson students use cabbage juice to test the pH of various liquids and then double check their work using pH probeware.

Engage

5 minutes

As the students enter the room, the pick up their Chromebooks, have a seat, and begin working on a Socrative quiz over acids and bases.  Socrative provides the students with immediate feedback, so they are able to see which answers were correct.  I am also able to view the results in real time.  Once everyone has finished with the quiz, we review the answers as a class and explain the reasoning behind correct answers.  The students did well with determining which of the items were acids and which ones were bases.  A majority of the students were also able to identify the products of a neutralization reaction.

Explore

30 minutes

The students begin working on their pH lab.  At this point, most of the students are ready to begin testing the various household liquids selected the day before.  As they test their liquids, I remind them to be sure to wash all of the items they are using each time they pour a liquid to ensure that they are not contaminating their samples. 

While the students work, I circulate through the room answering students questions and posing questions for deeper thought.  I also use my lab checklist, so students are more aware that their behavior and following proper lab procedure are important.  Students use the pH probes to find the actual pH of their chosen liquids.  If we are short on time, I have a group of students make a master list of pH and share it with the rest of the class.  The probes are also available to the students who would like to conduct additional testing to answer the lab question regarding how the addition of water impacts acids and/or bases. 

Working on the laboratory exercise helps to meet NGSS MS-PS1-2 as students are identifying the results of an chemical reaction to determine whether a substance is acidic or basic.  Additionally, the conclusion of the lab meets NGSS SP4 and SP8 as students are required to conduct an investigation to determine pH and then use data to support their findings.

As students finish up the lab, they clean up and are then participate in an online simulation that also uses cabbage juice as an indicator.  Alien Juice Bar is a simulation created by the Lawrence Livermore Lab, University of California, that provides students with three levels of play, each level building in degree of difficulty.

Wrap up

5 minutes

Once all of the students are finished with the lab, we discuss their findings.  Of particular interest is their response to the last question on the lab activity.  Many of the students have difficulty recalling the definition of acid rain, a term they covered the previous year.  The students also have difficulty explaining some of the factors for why acid rain could be a problem in aquatic environments.  This is a real world connection that I emphasize with the students, to ensure they understand the concept before they leave class.  It also ties in very nicely with our science club study of a local watershed area.