Teacher Portal

Properties of Matter: Investigation 4 –










Italicized font represents information to be shared orally or physically completed with the students at this time.

The non-italicized font represents additional information included to support the teacher’s understanding of the content being introduced within the CELL.


Remind students that by observing a sample of matter and measuring its chemical and physical properties, we gradually acquire enough information to characterize it and distinguish it from other kinds of matter. This is the first step in the development of chemical science, in which interest is focused on specific types of matter.


Remind students that biochemists study the chemical composition of living things. A biochemist might develop a vaccine to prevent a new strain of flu or new biofuels that could provide an alternative source of energy.


Inform students that the Investigation is designed to help them to answer the following Focus Questions: 

  • Can compounds composed of the same elements have a similar or dissimilar pH? Compounds composed of the same elements may have a pH that is either similar or dissimilar to each other.
  • Do all liquid compounds have the same pH? Why or why not? The pH of each liquid compound in our investigation was dissimilar from that of the other liquid compounds.
  • Do all solid compounds have the same pH? Why or why not? Yes and no.

Note: These questions are located in students’ SDRs at the beginning and end of the Investigation.

Note: These are succinct responses to the Focus Questions and are placed here for your reference at this time. Fully developed responses to the Focus Questions can be found on the PostLab page.


As a class, read the Background(s) in the Investigation. Have students read the information aloud or silently to themselves. When students have finished, discuss the following concepts as a class:

  • pH is a property of compounds used to describe whether a compound is an acid, base, or neutral substance.
  • The pH scale extends from 1 to 14.
  • Substances with a pH less than 7 are considered acidic. 
  • Substances with a pH greater than 7 are considered basic.
  • Substances with a pH of 7 are neutral.

Note: These concepts are integrated into the Background(s) and are used to deepen students’ comprehension of the big ideas.


The following list includes Key Terms that are introduced in the Investigation Background(s). They should be used, as appropriate, by teachers and students during everyday classroom discourse.

  • pH

Note: Definitions to these terms can be found on the Introduction page to the CELL.

Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.


  • Explain to students that they will investigate another property of compounds – pH. 
  • Introduce pH as a chemical property of substances. 
  • Explain that based on pH, substances are described as acidic, neutral or basic.
  • Explain that pH is often a property used to classify or categorize compounds.
  • Complete the Recall section in students’ SDRs.
  • Play the video below. Stop to ask students questions or answer students’ questions when necessary. Remind students to follow along with their SDRs and make any notes that they think might be helpful.
  • After the video, direct students to divide into their lab groups to discuss their strategy for the lab. For example, they may assign certain group members to perform specific functions during the lab.

Note: The purpose of the video is to allow students to anticipate the laboratory experience they will soon encounter. Students should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.


Tell students that they should review the Investigation in preparation for the Lab.