Separating Mixtures- Pre-Requisite

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Students will be able to understand the vocabulary that describes the process used to separate mixtures.

Big Idea

What types of processes do scientists and engineers us to separate mixtures?

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Purpose of Lesson:

 The purpose of this lesson is to give students some fluency with important vocabulary words and give them some demonstrations that they can latch onto later in this unit.


Major Strategies to Watch for:

1) Frayer Model-  This is a strategy for giving students depth on a certain important term.

2) Demonstrations- Lab demonstrations can give students visual memories that they can later access.

3) Vocabulary Activity- This collaborative activity gives students a method of using word clues, visual clues, definitions, and sentences to help students solidify their understanding of the terms.

Ready. Set. Engage!

5 minutes

Learning Goal: Understand the vocabulary that describes the process used to separate mixtures.

Opening Question: How could we separate alcohol and water? 

Students record their opening question on their learning goal sheet and are ready to start class 3 min after the bell has rung.  I reward students who get started early with ROCK STAR SCIENTIST tickets.  

Follow the links to learn more about the beginning of class strategies and ROCK STAR scientist tickets


5 minutes

This video is a very quick overview of how fractional distillation works. I like to show it to the students to continue stressing the point that most substances found in nature are mixtures, like crude oil, and that it takes complicated methods to both extract and separate the mixtures.  I ask students to watch the video and be able to tell me the name of a mixture in the video and how it is separated.

Important Prior Concepts

5 minutes

The purpose of this section is to use a vocabulary strategy to help students with the word mixture.  Frayer models are a great strategy to use when the vocabulary words have a lot of depth and complexity.  You don't want to overuse this strategy by attempting to apply it to every vocabulary word, instead save it for the terms that are crucial to the essential learnings.  

Below is a video of a focus lesson I give when teaching students to make frayers.  

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I'm attaching a blank template for Frayers, though I prefer to use 3X5 notecards which can be displayed easily in a Frayer Quilt. 

Sometimes I have the students put their frayer models in their lab notebooks so that we can access them easily.  Below is an example of student work in a notebook.  I like the examples and non-examples the student chose in their Frayer model.  I don't think they put enough thinking into their characteristics.  This would be something I would ask the student to fix later if they turned it in. 

Demonstration Activity

15 minutes

These two demonstrations are great for showing methods of separation of alcohol and water using characteristic properties.  In the first, I use the characteristic property of flammability.  To set this up you mix alcohol and water in a cup and add a dollar bill.  Carefully take the dollar bill out and use a lighter to set in on fire.  The alcohol will burn off but the dollar will still be wet.  This is a flashy and fun demonstration.  See the video below.  (I apologize for the video was done by my 8 year old!)


A less flashy but just as interesting demonstration is to use fractional distillation to separate a mixture of alcohol and water.  Use the set up below.  Because the students found the boiling points of alcohol and water in the previous unit, they should be able to easily understand that the alcohol will boil at about 78 C and the water will boil at 96 C (in Colorado!:) Simply move the distillation tube from one test tube to another at the right time to collect the alcohol and water separately.  

You can test the distillates afterward for flammability to prove that the substances are alcohol and water.   

Vocabulary Activity

10 minutes

Now that students are excited to learn about cells and know what they are going to learn about, it is a perfect time to introduce some vocabulary words.  I use a multimodality strategy to introduce only about five to seven words, and do this in collaborative groups of four with each person having an assigned job.  

1- Word person- states what they already know about the word or what the word means to them.

2- Image person- States what they think about the picture and what it means to them.  

3- Definition person- Reads the definition and states what it means to them.

4- Sentence Person- Reads the sentence and states what it means to them.  

I project the presentation on the board or put individual copies at the desks.  

I use a timer and a bell.  Each person gets 15 sec for their role.  In the beginning of the activity the students need to be trained on what to do and it helps to give them some sentence starters, like "This means..."  "When I hear this I think..."

After each person has rotated through their roles for the first word, I give the students 1-2 min of independent time to make their TIP charts (Term, Information, Picture) for that term. Then we move on as a class to the next term.  Later in the year, when students are familiar with the process this can be released to them to manage their time.  But in the beginning I manage the time to keep the class on track.

This work has meaning and purpose. Students keep these homemade glossaries in their folders and can use them on all the work we do in class including tests and quizzes.  This is a great resource for them to use the rest of the year!

Below is a picture of the slide for the word EVAPORATION and a video of the student discussion.


2 minutes

Closing Statement: Today we learned some vocabulary words that we will be able to use later in our units.  As we separate mixtures we will be using characteristic properties.

Closing Question:  How do you use characteristic properties when separating mixtures?

Closure depends greatly on timing and is not as easy to plan in advance as opening.  You can find more information about how I manage closure here.