Pumice vs Obsidian

9 teachers like this lesson
Print Lesson


SWBAT collect, record, and compare & contrast observational data.

Big Idea

Investigate. Make observations. Record Data. Compare & Contrast. Learning how to find how things are alike and different can help you understand the world around you.

Bell Ringer - How To Identify Luster

5 minutes

How to identify Luster

Before Viewing the Video:

Students need practice understanding each of the properties of minerals and luster can be a confusing property. This video helps to explain luster and show some examples of the luster of minerals. I ask students to use their Science Journal (Notebook) to record 2 ideas or words they learned in the video. 


After viewing the video:

I ask students to share what they learned. I do a quick whip around to hear student responses. It is important that other students hear responses as well because it help them process the information. I am looking for answers such as:

  • Luster is how the mineral reflects light. 
  • Luster can be glassy.
  • Luster can be metallic (or like a mirror).
  • Not a precise measurement.

Pumice vs Obsidian

30 minutes

On the Pumice vs Obsidian worksheet, I ask, "What is the difference between (the rocks) Pumice and Obsidian?" This question is the focus of the investigation. I read aloud the background information and ask students to take a "Vocab Minute" to highlight domain-specific vocabulary on the worksheet.

This new strategy of mine, "Vocab Minute", reminds students to take time to look for, highlight/circle, and be aware of science vocabulary in the text.

Next, working with their partner, students write an hypothesis. At this point in the year, I expect students to write a comprehensive hypothesis using the sentence frame printed on the worksheet. As students are working in partners, I circulate the classroom to see if they are on target. I ask 2-3 students to share their written hypothesis so that others can hear their thinking. I ask students to proceed with the investigation, provide supplies, and then circulate the classroom to talk with groups of students. I gather anecdotal data as I conference with groups of students and get some knowledge of their level of understanding.

This lesson focuses on several NGSS Science and Engineering Practices: 

SP1 Asking Questions and Defining Problems I want students to ask questions that can be investigated within the scope of the classroom and that require sufficient and appropriate empirical evidence to answer.

SP4 Analyzing and Interpreting Data I want students to analyze and interpret data to see if any patterns and relationships are revealed and to provide evidence for phenomena.

SP8 Obtaining, Evaluating, and Communicating Information I want students to obtain, evaluate, and communicate information because students need to develop the ability to read and produce domain specific text. In this lesson, students gather and synthesize information and will learn from and use this experience later in the unit during the summative assessment.

The lesson also focuses on two NGSS Crosscutting Concepts

Patterns - students will observe patterns in the natural world, describe this phenomena, and use it as evidence.

Structure and Function - students will understand the shape and stability of structures of natural objects and how they are related to their function.

As students learn how each of these rocks (pumice & obsidian) are formed, they will work towards mastery of the Performance Expectation (PE) MS-ESS3-1 construct a scientific explanation based on evidence for how the uneven distribution of Earth mineral, energy, and groundwater are the result of past and current geoscience processes.

Additionally, this lesson will guide students as they work towards mastery of the standard Earth Science Standard MS-ESS 3-3 which states that students will apply the scientific principles to design a method for monitoring and minimizing a human impact on the environment (mining). 

After students work with their partner to analyze the data, I facilitate a whole class discussion. I ask students to respond to the two questions: How are these rocks alike? How are these rocks different?To increase the rigor of the discourse, I remind students to use Discussion Moves (previously taught earlier in the year). Read more about Discussion Moves in this lesson.

Discussion Moves with Pumice vs Obsidian


5 minutes

I learned that . . . because . . .

Now, let's write a conclusion. As with any inquiry, sometimes students "get it" and sometimes they don't, but that ok. This provides opportunity to discuss what they observed and compare that with their peers. This step is very important for students to "come full circle."

I have learned that you need to take students back to the question so they can think about the process. What is the difference between Pumice and Obsidian? Take 1-2 minutes for students to process this question and write a conclusion. I give them a sentence starter to help with the process, for example:  I learned that . . .because. . .  Sentence Frames are especially helpful to Special Education and ELL students because they increase the rigor of the writing and guide student thinking. Take 1-2 minutes to share answers with the class so students can hear other student thoughts.