Semester Review Lab Day 1: Borax Ornaments

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Objective

Students will be able to demonstrate their understanding of multiple concepts including the periodic table, atoms, bonding, intermolecular forces, and stoichiometry as demonstrated from performing a lab to make Borax crystal ornaments.

Big Idea

Borax is a compound with characteristic properties that can be investigated while also doing a semester review.

Introduction

In this lesson students have a chance to review for their final exam while also performing a fun and engaging lab activity where they make borax ornaments.

  • Because this is a review activity it touches on multiple NGSS Performance Expectations including: 
  1. HS-PS1-1: Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
  2. HS-PS1-2: Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties. 
  3. HS-PS1-3: Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles.
  4. HS-PS1-7: Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.
  • This lesson aligns with NGSS Science and Engineering Practice 3: Planning and Carrying out Investigations because students are performing a lab.

For this lab activity there are several materials needed including:

  • One labeled container per group containing borax.
  • One hot plate per group (preferably with a stirring option)
  • One stir bar or stirring rod per group
  • One 1000mL beaker per group.
  • Conductivity testers at a separate lab station with borax dissolved in water. This shows how I set up the conductivity station.
  • Bunsen burners at a separate lab station with nichrome loop wires and borax in a labeled container. This shows how I set up the burning station.

 

 

Engage

2 minutes

To engage students in the lesson I review with them the fact that we have our final exam next week and that this lab is a great way for them to check their understanding of what we have learned during first semester.  With this being said I remind them that the goal is to remember the material so to try to make sure they understand the answers and not just copy from their classmates.

I also show students an example of the borax ornament from the previous year to give them a visual of what they will be making to get them excited for the lab.

Explain

10 minutes

In this part of the lesson I go over with students what they will be doing in the lab activity.  I also have them break into cooperative groups. 

  1. To begin I have students prepare for the activity by making sure that they have the lab, their binders, a periodic table, a calculator and their mole map. 
  2. I then go over safety with students and reiterate that they must wear their safety goggles when they are using the hot plate and the Bunsen Burners.
  3. I show students where the conductivity station is and review how to test conductivity (This is a picture of the conductivity station which has conductivity testers with a borax solution in a beaker below)
  4. I show students where the burning station is, review with them how to light the Bunsen Burner, and explain how to keep the station clean. (This is a picture of the burning station which has a Bunsen burner, a container of borax, a nichrome loop wire, a beaker of water, and a striker).
  5. I explain to students that when they are using the hot plates to make sure that they use the gloves when they are taking the borax solution off of the hot plate and to ask me for help if necessary.
  6. I tell students that when they are making their ornaments to use the supplies in their bag and that they will then tie onto a wooden stick and hang in a labeled styrofoam cup with a partners (This is a picture of the bag that I give to students).  That means that for their groups of 4 they will have two cups each with two ornaments.  I also make sure to note that the ornaments should be able to hang in the cups so they cannot make too large.
  7. I then break students into cooperative groups. 
    • I do this by giving students the roles of Primary Investigator, Post-Doc, Graduate Student, and Undergraduate Student.  I like to use the "real-world" lab roles to get them into the idea of who works in labs.
    • For this lab the roles include:
    • Primary Investigator as the person to keep students on track
    • Post Doc as the person to read instructions
    • Graduate student as the person who does the procedures
    • Undergraduate student as the person who cleans up
    • This is a picture of how I have it written on my board for my students.
    • If a group has 3 students I will combine the Primary Investigator with the Post Doc or if a group has 5 students that I will make two graduate students.
    • This Classroom Video explains the rationale for cooperative groups and shows students working in a cooperative group.
    • See my reflection on cooperative groups in unit 1 lesson 9: Density Part 2 and Review for further details.
  8. As a last note before I have them go to their groups I tell them to make sure that they are finding answers with their group FIRST and then if they can't find the answers in their notes that they should ask me as I am walking around.

 

Elaborate

90 minutes

This is the part of the lesson where students actually do the lab.   They are working in their groups at their tables and filling in answers on the Lab Paper as they go.

I walk around and check their work to make sure they are doing the work correctly while also answering questions from students.  I try to not give students answers, but rather give them hints of where they should look to find answers on their own.  This video shows how I help one group do this.

Some examples of the questions I ask include:

  • How did you figure out the number of neutrons?
  • How do you know the order of increasing ionization energy?
  • Why do you expect Borax to conduct electricity?
  • Why do you expect Borax to not burn?
  • How do you know that Borax will probably have a high melting point?
  • How do you determine percent composition?

Some common confusions among groups include:

  • Determining number of neutrons
  • Figuring out electron configuration
  • Figuring out the charge of the atom (I have to remind them that this is determined based on group)
  • Rating the trends of the elements
  • Knowing that borax is ionic (should include the compound in that question)
  • Knowing the intermolecular force for borax
  • Definition for atomic size (its not in the book so have to look at notes)
  • Being able to perform the 3-step conversion in questions #8.  This video shows me helping a student solve this problem.

I find that some groups move slower than others so in order to keep all students at a pace where they will finish the lab by the end of class I stop students when there is about 30 minute left in class.  I tell them that whether or not they are done with the questions on the previous pages that they should be onto the last page and beginning to make their ornaments.  This video shows how I do this in my classroom.

When students are done with their lab I have them bring their ornaments in the Styrofoam cups to the back of the classroom and I put them in bins according to class period.  This Ornament Storage Picture shows how I do this.

Finally, at the end of the class I give a quick summary of what we did in the lab for day 1 and let students know what they will be doing the following day for day 2 of the lab.  This video captures how I do this in my classroom.

Evaluate

Students do not turn in the lab until they complete day 2 in the next lesson: Semester Review Lab Day 2 and Final Review Bingo

When I do grade the lab I do not grade it for correct answers, rather I grade it for completion. 

Students earn a "check" (100% credit) if they have most of the lab complete (only missing up to 3 answers)

Students earn a "check minus" (75% credit) if they are missing some of the lab (like a page worth of information is missing)

Students earn a "check minus minus" (50% credit) if they are missing quite a bit of the lab (like almost two pages worth missing)

Here are two Examples of student work (Example #1 and Example #2 ).  Notice how these students answer the questions and show their work.