Low stress chemistry with “hands-on” stoichiometry
[This article comes from a blog called Sustainable School Teacher . I recommend you watch the blog’s 10-minute video because Brandie outlines her idea to introduce a hands-on approach to stoichiometry. Once you watch this video you will want to investigate her other ideas. This heartfelt blog is full of insights into teaching chemistry and life as a teacher. ]
The purpose of my blog is to help other teachers reduce the stress in their lives and to allow me to reflect and continue my own personal growth. In that vein, any chemistry teacher can tell you that stoichiometry is easily one of the most frustrating topics to instruct, so I wanted to share a strategy I created that has been well-received by both my students and fellow educators.
In addition to making our jobs easier, it is critical to reduce rote learning via the use of algorithmic flowcharts, which do not foster conceptual understanding and may lead to confusion if not used properly.
After seeing my lowest students internalize molar conversions kinesthetically — even after the marker ink on their hands has washed away — I will never go back. As I mentioned in the condensed video, the parts of our brains that process numerical representation also control our finger movement. So, a literal hands-on approach is a great way to help students who struggle in math be successful in stoichiometry. I invite you to try it yourself; invest 10 minutes so you can return with fewer paper corrections and tutoring sessions. I promise!
Basically, in the video I show how students can label their palms and fingers — this will be their stoichiometry flow chart.
I start with one hand — labelling the palm “moles”. The fingers are labelled with FAM (formula units, atoms and molecules) (Fig. 1), mass and litres (Fig. 2). Starting off, students learn that to convert from units on one finger (i.e., mass) to the next (i.e., atoms), they must put their palms (the mole) together.
Once they are comfortable, students write moles of A on one palm and moles of B on the other (Fig. 3). Their fingers are still labelled with FAM, mass and litres. To go from one type of substance to another, they put their palms together to remember they must go through moles in the balanced chemical equation to convert. The trick is, the labels provide the map to the conversion — see Fig. 4. To convert from mass of A (finger on left) to, let’s say, molecules of B (finger on right), students must go through moles (their palms). If you watch the video, it will make sense, and I explain how I introduce this method to students.
Here are some quick tips for pulling this off from my experience and other teachers' feedback:
- Students with sensory processing issues may find the marker on their skin unbearable. In this situation, you can give them the handout I used in the video. If a student’s parents would prefer they not write on their hands, disposable gloves can also be used (and reused for the duration of the unit).
- It is best not to have students fold their fingers down while converting lest birds* be shot in your classroom. Kids will be kids, and we have enough behavior issues to handle already.
- Each lesson adds a new type of conversion instead of starting with all three fingers labelled at the beginning. The first day, for example, students may only have particles (formula units, atoms and molecules) and moles on their hand. The next day, grams can be written and utilized.
- Fine-tipped washable markers work well for this activity because they are the least permanent, and the kids enjoy the colors available. Plus, they are less likely to vanish from your room than Sharpies.
If you are interested, go to my blog for a handout of my practice problems.
I wish you the best of luck and a mole of “A”s on your next stoich test.
*(raised middle fingers)
Fig. 1. Students start by labeling one hand and finger - convert atoms to mole.
Fig. 2. Adding more units to fingers. Students convert from grams to litres using moles.
Fig. 3. The students label their palms and the fingers of both hands to prepare to convert from moles of A to moles of B.
Fig. 4. To convert from mass of A to atoms of B, students must put their palms together - go through moles using the balanced chemical equation. This gives students the pathway to understand stoichiometry.