422 What Makes Tweetorials Tick: How Experts Communicate Complex Topics on Twiter KATY ILONKA GERO, Columbia University, USA VIVIAN LIU, Columbia University, USA SARAH HUANG, Barnard College, USA JENNIFER LEE, Columbia University, USA LYDIA B. CHILTON, Columbia University, USA People are increasingly geting information and news from social media. On Twiter we are seeing the emergence of “tweetorials” – long, explanatory Twiter threads writen by experts. In this work we study tweetorials as a form of science writing. While scientists have begun to champion the importance of Twiter as a science communication medium, few have studied how people are successfully using this medium to communicate complex and nuanced ideas. To understand how tweetorials work, we curated a collection of 46 clear and engaging tweetorials from multiple domains. We analyzed these tweetorials for the writing techniques that they employ, and found that while tweetorials use many traditional science writing techniques, they also use more subjective language, actively build credibility, and incorporate media in unique ways. In addition, we report on a workshop we ran to aid science PhD students in writing tweetorials, and fnd that while providing common tweetorial techniques improves their writing, the students still struggle to balance their scientifc sensibilities with the informal tone associated with tweetorials. We discuss the implications of using informal and subjective language in science communication, as well as how technology can support scientists in writing tweetorials. CCS Concepts: • Human-centered computing → Collaborative and social computing;• Applied com- puting → Education. Additional Key Words and Phrases: Science communication, science writing, social media, Twiter, tweetorials ACM Reference Format: Katy Ilonka Gero, Vivian Liu, Sarah Huang, Jennifer Lee, and Lydia B. Chilton. 2021. What Makes Tweetorials Tick: How Experts Communicate Complex Topics on Twiter. Proc. ACM Hum.-Comput. Interact. 5, CSCW2, Article 422 (October 2021), 26 pages. https://doi.org/10.1145/3479566 1 INTRODUCTION More and more people are learning about the world not from newspapers or magazines, but from social media [49]. Tis information can come directly from experts, who have found social media to be a straightforward and low-barrier way to communicate their expertise to the public [52]. In particular, Twiter has become a popular platform for experts of all kinds. While academic communities on Twiter have been studied extensively [19, 35, 46], with a particular focus on how Authors’ addresses: Katy Ilonka Gero, katy@cs.columbia.edu, Columbia University, New York City, New York, USA; Vivian Liu, vivian.l@columbia.edu, Columbia University, NewYork City, New York, USA; Sarah Huang, Barnard College, New York City, New York, USA; Jennifer Lee, Columbia University, New York City, New York, USA; Lydia B. Chilton, Columbia University, New York City, New York, USA. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for proft or commercial advantage and that copies bear this notice and the full citation on the frst page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permited. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specifc permission and/or a fee. Request permissions from permissions@acm.org. © 2021 Association for Computing Machinery. 2573-0142/2021/10-ART422 $15.00 https://doi.org/10.1145/3479566 Proc. ACM Hum.-Comput. Interact., Vol. 5, No. CSCW2, Article 422. Publication date: October 2021.