The Alchemie of Arrows

March 17, 2021
Company & TechnologyGianna Manchester

Alchemie has a long history with curved arrows in mechanisms - or the lack thereof.


When we first developed the Mechanisms app, we were determined to do mechanisms in a different way that would allow students to understand the movement of electrons better. When debating how to do this, our CTO, Joe, insightfully pointed out that arrows are an artifact of drawing mechanisms on paper. But when you do a mechanism digitally within the app, your finger is used to move the electrons, eliminating the need for an arrow to show that movement. Nevertheless, your finger would also cover the arrow head and you wouldn’t be able to see it anyways.

Screenshot of the Mechanisms app showing electrons moving from an oxygen moving to a carbon. There is a sillohete showing that a user would use their finger to move them.
Screen shot of arrow-pushing in the Mechanisms App. The hand silhouette represents how a user uses the interface to manipulate the electrons.

Although we received some pushback from instructors, we ultimately found that students better understand the movement of electrons using the Mechanisms app because they are actually moving the electrons opposed to drawing arrows to symbolize this movement -- a representation that often leaves students confused as to what is actually happening.

Alchemie has stood by this philosophy since the beginning. That is, until we were designing our new 3D mechanism tool and our Lead Developer, Jeremy, included an image of a cursor to draw attention to the movement of electrons in a mechanism replay. The cursor made it resemble an arrow and the content team’s eyebrows raised in excitement.


Capture of the work in development version of 3D Mechanisms where we temporarily replaces the end of a electron edit with a giant arrow icon. inspiring the push to 3D arrows.
Capture of 3D Mechanisms in Development


From there, Jeremy presented various arrows and ways of showing them. 

As someone who has been a wholeheartedly happy passenger on Alchemie’s train of no arrows since working here, let me tell you, these arrows are absolutely gorgeous. In addition to being in 3D, we are allowing users to see mechanisms in a way that they have never seen before. 

The difference between drawing arrows on paper and the arrows in Alchemie’s mechanisms is that ours are followed by an animation of the electrons moving, allowing for students to connect the arrow they drew to the movement of electrons that actually happens, solidifying their representational competence.

3D Arrows Screen capture of 3D arrows being used in a 3D SN2 mechanism of methylbromide and hydroxide. The mouse is shown drawing an arrow from a lone pair on oxygen to the carbon, then another arrow being drawn from the carbon-bromine bond to bromine. The user then taps a red button with the word "push" on it to view the movement of electrons when forming and breaking the bonds.
Screen captured turn table view of a 3D Mechanisms showing the 3D arrows.
Screen Captures of Mechanisms in 3D


Alchemie has released some pretty revolutionary learning tools, but this one is probably the one I have been most excited for, and I can’t wait for instructors and students to test it out in our newly designed learning system this summer! ;)

Are you interested in reimagining the digital component of your course? Tell us what you would want here

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