A Look Into My General Chemistry Reactions Unit- Supporting Students with Making Connections among the Nanoscopic and Macroscopic

dissolving

Organic chemistry was when I fell in love with chemistry. Also known as Chem 210 at the University of Michigan, it was the first time I actually started to connect what was going on at the nanoscopic level to the macroscopic world. Since then, I’ve been hooked.

 

As a teacher, I have grown a lot over seven years (including student teaching). How do I get my students to make connections to the nanoscopic without, you know, curved arrow mechanisms? I have been fortunate throughout the years to piece by piece gain new perspectives that I thought I’d summarize and share with you - in fact, I’ve effectively rearranged my whole first year chemistry course to be built upon a progressively more in depth view of the nanoscopic. In this post, I will focus on only my reactions unit. This is in the second semester after students learn about the mole and empirical formula.

 

In our reactions unit in the second semester, we go all in.

 

  1. First, students learn how to balance, classify reaction types, and predict products.

 

This part is where my former mentor, Julie Andrew of CU Boulder, really helped take this unit to the next level. She (that I’ve edited from her original document) where not only do students practice predicting products, but they get practice in experiencing when predictions fail. Some of the reactions are designed so that they get results that DON’T match their predictions. This allows for students to (1) make a real conclusion if their predictions matched their observations and (2) ask new questions that lead me to showing splint tests. Here is an example. When students predict the products for the reaction of hydrochloric acid and sodium bicarbonate, they predict sodium chloride and carbonic acid, since they see it as a double replacement. This is 100% valid based on what they have learned. However, this is what actually happens: HCl + NaHCO3 → NaCl + H2O + CO2.

 

In our whole class debrief, we go through EVERY reaction after they share their data on the board. I tell them they are smart for making that prediction once they find it fails- it’s what scientists do ALL the time- make predictions based on prior knowledge to sometimes find that they were wrong. It is helpful to give them the "maybe" option. See a sample class data set below- this gave us great ways to start class conversations.

 



 

B. Here’s where we dive into the nanoscopic - the animation project. I introduce the project, and then do a few lessons first.

    1. Lesson: (edited from a posted PHET - credit is within the document). My students really struggled with the vocabulary of dissolve vs. dissociate, even though they could find errors in particulate diagrams. So the next day, this was their warm up. It was quite telling (PS- yes the phosphate has dissolved in water and has dissociated from the sodium. However, the phosphate ion itself doesn’t dissociate further).

    1. Notes: Redox vs. Precipitation Reactions

    2. Now, groups of 2-4 students to connect the nano and macroscopic representations. They must choose a precipitation reaction and a redox reaction. Here is a link to .

One Bigger Con:

  1. Time. It takes time to teach this and time to make the animation. I have posted a pseudo-POGIL-style PHET activity below that prepared students for animations. I also posted the project guidelines (thank you Julie Andrew at CU Boulder for the nuts and bolts of this!!!!!). Word of the wise: google slides is also awesome, and in some cases, more awesome than ChemSense referenced in the instructions.

A Few Pros:

  1. Time “lost” in this project reaps benefits in dividends in stoichiometry. This is the first year (!!!) I’ve taught stoichiometry with BCA tables and the animation projects before were an unintentionally amazing scaffold. I have NEVER seen my students so successful with stoichiometry as I’m seeing now, and my hunch is that the animation projects helped make the BCA tables more accessible.

  2. I sent the animations to MEL Science. They haven’t gotten back to us yet, but my students were pretty stoked to send off the animations to a company for feedback.



My Tweet

Their Response (so far)

I hope this is helpful and sparks ideas for the future, and I’d love to hear more of what you do too!

 

 

 

NGSS

Students who demonstrate understanding can 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.

*More information about all DCI for HS-PS1 can be found at  and further resources at .

Summary:

Students who demonstrate understanding can 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.

Assessment Boundary:

Assessment is limited to chemical reactions involving main group elements and combustion reactions.

Clarification:

Examples of chemical reactions could include the reaction of sodium and chlorine, of carbon and oxygen, or of carbon and hydrogen.

Join the conversation.

Comments 2

Suzanne Irwin | Thu, 06/02/2016 - 11:07

Hi, Thank you so much for posting this and sharing all this detail!  I am a second year teacher, and for the past two years I have tried different ways to make connections between the nanoscopic and macroscopic.  I am very interested in trying this next year, and I have a couple of questions for you.  First, how much time did you allow (in and out of class) for the students to do the video project?  Second, had they ever done a project using similar technology, or was using the technology of the animation new to them as well?  Third, it seems that you are teaching this in the middle of your second semester.  I am curious about your pacing and student's background knowledge.  Based on observations and data from my first year, I rearranged my pacing so that I could teach stoichiometry (which I would teach after this) before the end of the first semester/at the beginning of second.  We can have so many snow days here in Virginia that trying to teach that concept in Feb./March can be very difficult.  I also found in my first year that students had a very difficult time understanding the abstract nature of atomic structure, so my pacing is more macro to micro now.  My students also have a very difficult time grasping the idea of negative and positive charge in an ion. (I think continuing to drive connections to the nanoscopic will help that). I think to get into the details of dissolving and dissociating earlier in my year will work, but I will have to rearrange my order a bit and  bring some discussion of atomic structure into my pacing before doing that. Anyway, long explanation, but if you were willing to share any more details of your pacing I would be interested.  Also--I loved the lab from Julie Andrew that highlighted that not all predictions of products work out as expected.  One of the problems I have when teaching predictions is that it implies to students that you can predict what will happen, when really chemistry and science are based on experimental results.  So, thanks for that too!  I won't be doing this until next year but when I do, I will let you know how it goes!  Thanks so much!

Tracy.Schloemer's picture
Tracy.Schloemer | Sun, 06/05/2016 - 19:21

Hi Suzanne-

Thank you so much for reading and your questions! I feel the same way about Julie's lab - and done well, it is transformative to students (for my students, year one of implementation was meh, but this year hit the transformative mark). Here are responses below, and don't be a stranger!

1. For the animation project: 3 days in class (55 minute periods)

  • 1 day to storyboard (I had them do this by hand...that was a not awesome idea. I thought that it would promote more detail, especially since they'd have to translate it to a digital format, but I was wrong. Oops. I recommend google slides).
  • 1 day to peer review and then go through feedback.
  • 1 day to just work

2. Yes, my students had done video stuff in many other classes, but making a screencast was new for many of them. After the peer review, we brainstormed a list of ways to make a screencast for free from their digital animations, and I did zero tutorials in class outside of making this list. If you are worried about the tech, one thing a group did (because they were being creative, not because they had to) was do a stop motion animation on a whiteboard and filmed with their phones. I'm not sure what the level of tech is at your school, but is there is any available, your kids will likely teach you! (I had only heard of half of these items below)

    • Mac- quicktime for a screen recording

    • Open Broadcaster Software (OBS) - internet - screen recording

    • Camstudio

    • Screencast o matic

    • Save slides as image, put in gif making software…

3. My scope and sequence is more of a nano to macro view. My students who struggle with numeracy have a similar struggle with ions and charges - I see it every year as I continue to tweak curriculum to support them. In my scope and sequence, the excessive spiraling of content and themes over time often helps but is not a magic cure all.

Anyways, I have been thinking about writing a blog post about scope and sequence, so I think I'll do that sooner than later. Here is a short response copied from my syllabus:

CHEMISTRY/HONORS CHEMISTRY CONTENT

1st Semester

  • Nature of Science

  • Defining matter, measurement, conversions, and sig figs

  • Kinetic molecular theory of matter, gas laws

  • Chemical names and symbols, conservation of matter, properties of elements on the periodic table

  • Models of the atom, isotopes

  • Ionic compounds

  • Types of bonding and properties

  • Lewis structures, geometry, polarity, and intermolecular forces

  • Honors/Level 2: Intro to quantum theory, etc. More of the honors/L2 curriculum is embedded over time.

2nd Semester

  • Continue: Lewis structures, geometry, polarity, and intermolecular forces

  • Honors/Level 2: 3D molecules: chirality (mirror image isomers), amino acids and proteins

  • Chemical equations, physical and chemical change, balancing equations, types of reactions

  • The mole, counting by weighing, comparing amounts

  • Acids and bases, solution chemistry

  • Stoichiometry, limiting reactants, and percent yield

  • Honors/L2: equilibrium, etc. More of the honors/L2 curriculum is embedded over time.