Pity the poor teaching assistant, and a history of chemical notation.

Being a teaching assistant (TA) is as much a learning experience as a teaching experience, a fact most apparent in the student evaluations that TAs are handed at the end of the semester. These evaluations put the spotlight on those who have been accustomed to putting it on others. On his blog, Chembark (http://go.nature.com/WrvJCs) has a whole two-courses worth of student evaluations that convey his lesson that “teaching is excellent at identifying even the smallest gaps in your knowledge, as students are quite proficient at exposing inconsistencies in the material presented to them.”

Meanwhile, Master Organic Chemistry (http://go.nature.com/QaAIHX) implores undergraduates to know thy TA and realize that the TA is essentially a poor graduate student whose main allegiance is to his or her research.

And speaking of the basic chemical principles that TAs try to drill into their students' heads, do you know where those much feared and respected curly arrows came from? Henry Rzepa (http://go.nature.com/xADRsc) traces their origins to a 1924 paper by the famous Robert Robinson. Rzepa analyses Robinson's curly arrows and finds a few deficiencies in them that diligent undergraduates should be able to point out to their TAs.

Finally, Rzepa provides us with another window into chemical history (http://go.nature.com/b4ViAL) by looking for the first noted instances of the ubiquitous wedges and dashed lines that indicate stereochemistry. After examining the work of two masters of the art — Derek Barton and R. B. Woodward — a commenter points us to a fascinating collection of articles on chemical history by William Jensen that locates the first wedges and dashes in a 1932 paper by R. Kuhn.