Pivotal Bloggers: Starting IB Chemistry with Stoichiometry

November 9, 2021

Pivot Interactives was founded four years ago by two teachers who wanted to help science teachers everywhere explore scientific phenomena. Today, Pivot Interactives continues to be powered by teachers, with more than a dozen educators working to write content, develop the platform, and support our teacher users. We know that there are teachers all around the world doing incredible work to inspire their students and help them explore their world as scientists. This year, we want to celebrate and share that work, so we’ve invited a number of teachers to share windows into their classrooms by writing a regular series of blog posts about their teaching. We hope you’ll find these blog posts helpful, informative, and inspiring.

Hello, my name is Scott Milam and I do studio work and activity writing for PIVOT Interactives. I also teach IB Chemistry HL and chemistry at Plymouth High School in Michigan. This is my 16th year of teaching and I’ve been using modeling instruction for 7 of those. 

Our International Baccalaureate (IB) program is set up where we get students for a year of chemistry in 10th grade. The students who continue into IB Chemistry HL get another two full years of instruction. These three years allow me to spend the time to get to a deep level of understanding. But this current cohort of seniors has had an extremely unusual and challenging two years. To start out their first week we started by constructing whiteboards of what they remembered from the previous year. Most whiteboards focused heavily on organic chemistry. 

This is a powerful exercise because it utilizes the two most effective cognitive science strategies; retrieval practice and spaced practice. Retrieval practice is when information is retrieved from the brain directly. The opposite would be using a reference such as a textbook, video, or notes. The process of retrieving information from the brain requires practice to help lock in neural pathways. Retrieval is often more difficult, which causes students to avoid it. But it is a far more effective method of learning in spite of how it makes students feel. 

Spaced practice is about learning, forgetting, and then learning again. As soon as we stop learning something, our brain begins to revert back to its previous form. When we repeat the same thing multiple times after forgetting, our brain is designed to value that information more and limit the reversion. When we start the year by constructing these whiteboards it helps students to remind them of the previous content they studied. This will help as they learn new chemistry topics this year. I want to use these two methods frequently throughout the year. We often start class with the simple question of what is something we remember from yesterday? But we also want to periodically refer back to content from weeks or months prior. 

These seniors have had a tumultuous path to this point. They had school shut down as sophomores. Last year they switched from virtual, to hybrid, to in-person instruction. They have had quarantines, trauma, depression, and a large amount of uncertainty about their futures. Our goals this year are to focus on setting smaller chunk goals. Academically we’re focusing on acquiring new chemistry knowledge every day. We will worry about the exams when they approach. But for now we want to learn as much as possible this week. When we get to April and May, we’ll have the time to sort out the confusions. The end of the year is when students are most capable of learning chemistry as they have such a large repertoire of knowledge to pull from. 

This week we are starting stoichiometry. The students had some instruction on stoichiometry right before the shut down in March of 2019. I want them to end stoichiometry by understanding that chemical reactions are recipes that allow us to predict how much chemical will be produced or consumed. I want them to understand how useful moles are in simplifying those predictions. And I want them to know that there are three common methods for getting to moles. We can use concentration of solutions, we can use volumes of gases, and we can use masses of substances. Each of these requires some additional information, but knowing that the goal is to get to moles helps us to organize what we know. 

We used one of the PIVOT Interactive activities to help us with this. This chemical reaction takes solid magnesium metal and adds it to a solution of hydrochloric acid. Gaseous hydrogen is produced and the volume is measured. Here the students are seeing a macroscopic level visual of all three components that I want them to connect to moles. We used the mass of Magnesium metal to determine the minimum concentration of HCl required. We then predicted the amount of hydrogen gas that should be produced before checking the video to confirm our assumptions and calculations. 

Because the PIVOT is readily available I am able to focus my attention on instruction while still providing a phenomenon for students to engage with the abstract components of the lesson. We were also able to review oxidation and reduction by running through how the magnesium changes from neutral to 2+ charge. The hydrogen changes from 1+ to neutral molecules. We used plum-pudding models to connect the transfer of electrons to how the balanced reaction also includes charge balancing. Overall it was a rich and memorable experience that students drew a lot of understanding from. Even though our focus was on stoichiometry, there was review of redox chemistry, bonding, and reaction types in this one lesson.