Classifying the Universe: What is matter and how do we as scientists categorize it?

Lesson Content

• Lesson Plan Template:

  General Lesson Plan

• Learning Objectives: What should students know and be able to do as a result of this lesson?

  
  

  Students will be able to:

  • compare and contrast mixtures and pure substances.
  • distinguish between elements, compounds and mixtures and give examples of each.
  • draw a particle representation of an element, compound and mixture.
  • classify mixtures as homogenous or heterogeneous and give examples.

• Prior Knowledge: What prior knowledge should students have for this lesson?

  
  

  Students should:

  • be familiar with the periodic table and how to identify and locate elements on it.
  • know and be able to differentiate between the four phases of matter.
  • know that atoms are the smallest particles of a substance that combine to produce the objects of everyday life.

• Guiding Questions: What are the guiding questions for this lesson?

  
  

  What is the difference between oxygen and carbon dioxide?

  • Oxygen is an element while carbon dioxide is a compound.

  How would you classify the air you breath?

  • Students may first assume that air is a pure substance because they may not know that air consists of nitrogen, oxygen, argon and other gases, making it a homogenous mixture. A homogenous mixture is a mixture consisting of a uniform distribution of the substances.

  Would salad dressing be considered a heterogeneous or homogenous mixture?

  • Students may answer both depending on how they are thinking about salad dressing. Salad dressing is a heterogeneous mixture because it does not have a uniform consistency. You can see the oil and vinegar separated in the bottle. However, some students may say homogenous mixture because when you shake the salad dressing, for a short period of time it may appear as though it is homogenous. Once you set the bottle down, however, it will separate again. You may demonstrate this in class.

• Teaching Phase: How will the teacher present the concept or skill to students?

  
  

  The instructor will facilitate note-taking and discussion using a PowerPoint presentation.

  Slide 2: Ask students what the difference is between a mixture and a pure substance. Student answers may vary, but they should eventually arrive at the conclusion that a mixture is "different things mixed together" while pure substances are "just one thing," or something similar. The instructor will then ask what the prefixes "hetero" and "homo" mean, and students should know hetero- means different while homo- means the same. The instructor can then question students about the difference between a homogeneous mixture and heterogeneous mixture is, asking for examples of each. Finally, the instructor will ask what elements are and where a list of elements can be found. They should answer that elements are the "building blocks of substances" or the "smallest pieces of elements," and that the periodic table is a list of the elements. The instructor can ask what a compound is, but it is unlikely students will have any prior knowledge.

  Slide 3: Explain that everything is matter, even things we are not able to see, such as air.

  Slide 4: Explain the difference between mixtures and pure substances.

  Slide 5: Explain the difference between compounds and elements, using clay to represent particles and describe how even though a compound has different elements bonded together, every "piece" of matter (meaning every molecule/formula unit) is the same.

  Slide 6: Introduce the concept of the indivisibility of the atom and how each atom of a particular element looks the same. For instance, a silver atom found in the ground in South America is the same as a silver atom in a necklace belonging to someone in the classroom.

  Slide 7: Reinforce the concept of compounds as pure substances, even though they are composed of different elements.

  Slide 8: Explain heterogeneous and homogeneous mixtures and ask for examples of each.

  Slide 9: Reinforce the concept of mixtures as substances where "not every molecule is the same," i.e. salt water.

  Slide 10: Explain how mixtures can be composed of any combination of states of matter and ask for additional examples of each.

  Slide 11-12 of the PowerPoint presentation will be used as the Guided Practice portion.

  Classification_of_Matter_PPT.pptx

• Guided Practice: What activities or exercises will the students complete with teacher guidance?

  
  

  Slide 11 of the PowerPoint presentation asks the students to classify different substances as elements, compounds, heterogeneous mixtures, or homogeneous mixtures. This activity will be completed as a class with the instructor giving immediate feedback regarding incorrect answers. If the instructor feels it is necessary, then more questions could be created and asked.

• Independent Practice: What activities or exercises will students complete to reinforce the concepts and skills developed in the lesson?

  
  

  Students will complete the following two activities either individually or as a group: Classification_of_Matter_Activities_Worksheet.docx

• Closure: How will the teacher assist students in organizing the knowledge gained in the lesson?

  
  

  The instructor will administer an appropriate exit slip of their choosing or ask students to summarize what they learned for the day in their notes.

  If you chose to use an exit slip quiz, you can use the data to calculate what student's mastery was and if it will be necessary to review key points next class. A quiz also allows for students to review and see where they made mistakes, and helps them ask questions in the beginning of the next class before moving on to the next topic. It is good to keep data on students' mastery and to use it effectively to measure where students did not understand. This will give you time to correct any misunderstandings before moving on to the next objective.

  During an exit slip quiz, be explicit about classroom expectations. Inform students that the assignment will be graded and counted as a quiz and if they talk, use cell phones or attempt to copy their neighbor, their quiz will be collected and counted as a zero. If your classroom is large enough, separate students from one another so they cannot see each other's answers. Remember, the data from these will be used to calculate mastery, so you want it to be as accurate as possible. Below is an example exit slip quiz you could use to test mastery.

  Exit_Slip_Quiz_Classification_of_Matter_Student_Copy.docx

  Exit_Slip_Quiz_Classification_of_Matter_Teacher_Copy.docx

• Summative Assessment

  
  

  Upon completion of the lesson, students will complete an exit slip assessment that will have questions about the material covered during the lesson and activities. These quizzes will be graded and used to determine student mastery of the objectives. Students need to score at least 80% for mastery. Use the data calculated to review material during the next class meeting and discuss major points of concepts that students did not master.

  The teacher will hand back quizzes so students can see their mistakes and ask clarifying questions. Exit slip quizzes should not include more than 5 questions. The questions are on the major key points that students need to understand in order to continue with the next objective. For an example of an exit slip quiz, see the Closure section.

• Formative Assessment

  
  

  The teacher will begin class by posing questions that will lead into the lesson.

  Here I have a glass of water with salt in it. You can see the salt accumulated at the bottom of the beaker. When I mix them together, notice that the salt has dissolved. Is there a way I can separate the salt from the water?

  Students raise theirs hands, state their answers, and explain why they think it can/cannot be. Answers will vary. If a student calls out, redirect the class attention to the class expectations of raising your hand to respond to a question. If a student responds to the questions with, "yes," but is not sure of how or why, probe him or her into thinking of ways you may be able to remove the water. Do not accept simple yes or no responses. Have students explicitly explain their reasoning.

  Possible student answers:

  • "Dump the water out." But if I dump the water out, the salt will also go down the drain.
  • "Put the water through a strainer." The salt has already dissolved; the strainer would not be able to catch the grains.

  Have students keep giving suggestions, and eventually suggest that if we boil the water, it will change from a liquid to gas form, called evaporation, and will leave the salt in the beaker.

  Okay, we saw how the water evaporated and left behind the salt. Now let's say I have a beaker full of water. We know that the formula for water is H₂O. Can I break water down into hydrogen and oxygen?

  Students answers will vary. Explain:

  The answer would be no, not through physical means (like boiling). The reason is water is actually a compound. Compounds cannot be separated using physical means, but can be separated by chemical means. We will discuss this further in detail today. Some of you may be wondering why we could separate the salt from the water. That is because that was an example of a mixture and can be separated by physical means.
  
  Finally, let's take a look at this piece of aluminum foil.

  The teacher can just hold up a piece of foil, or pass some samples around and have students analyze it and try to determine if anything else makes up the foil.

  This is made up of aluminum, which is found on the periodic table. What do we know about the periodic table? What does it consist of?

  Students should be familiar with the periodic table of elements, or should be able to identify that it is an element. If not, be sure to review this prior to the lesson.

  It is made up of elements. Can elements be broken down?

  Students responses will vary. Explain:

  What is aluminum made of? We know that the symbol is Al, does this include anything else?
  
  No, an element is the smallest building block of matter. They are pure substances; they are all made up of the same thing. Remember, water and salt consists of both water and the salt, therefore, it has two different items, which is why it is a mixture. Today's activities will help clarify the differences between mixtures, compounds and elements.

• Feedback to Students

  
  

  During the discussion, the teacher can lead the students to different resources that can help them determine an answer or formulate an explanation. Provide students with a copy of the periodic table and write the symbols and formulas on the board. For example, by showing students that water is made up of H₂O, they will be able to see that water is made up of hydrogen and oxygen. They can reference their periodic tables to see that they are two different elements, and therefore, cannot be a pure substance. When they locate Al, they will see that it is an element, therefore, aluminum is a pure substance.

  Be sure to explain that when a lower case letter is next to an upper case letter, it is one element. If you have two upper cases, such a NO, students must be able to understand and identify that it is two different elements.

  For the introduction, students will be guided by the teacher and will be receive immediate feedback. The teacher can probe students for deeper understanding and explanation by asking clarifying questions based on the responses given by the student. This will vary based on the responses and how in depth the teacher wants to explain. Remember this is just an opening activity to get students interested in the lesson. During the activities, students will work in small groups and will be able to peer review until final review by the instructor. The final summative assessment will be graded and returned to students next class and the instructor will review the assessment before beginning the next lesson to ensure students are aware of where they made mistakes and have a chance to ask questions.