The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25–50%) than euchromatic reference regions (3–11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11–27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4–3.6 vs. 8.4–8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu.

For about a century, textbooks have provided a consistent framework for faculty to teach fundamental, common courses across colleges and universities. However, little quantification of students’ textbook reading is documented in higher education. An interactive textbook from zyBooks documents students reading through clicks. With large data sets, including three cohorts with over 280 students and 280,000 reading interactions, measurable differences between students were found using effort‐based reading analytics. Median textbook reading participation at the due date above 90%, which is significantly higher than reports and surveys in the literature. Reading participation increased with every higher final course grade, and a statistically significant difference in reading participation between B and C students was measured. Also, female students read statistically significantly more than male students. Additional reading data taken at the conclusion of the semester found that many students completed reading without the incentive of earning a course grade. Median reading participation increased after the due date, which encompassed 30 to 50 clicks by median and over 400 interactions for some students. Overall, interactive textbooks generate large data sets that monitor reading participation and reinforce proven study practices, such as spaced practice.

and expects to earn a BS degree in 2021. She has assisted with multiple areas of research and data analysis regarding zyBooks reading participation and challenge activities. She became interested in performing research after completing a chemical engineering course that used zyBooks.

is a Professor of Chemical Engineering at the University of Toledo. He earned a B.S. degree from the University of Illinois at Chicago and M.S. and Ph.D. degrees from the University of Illinois at Urbana-Champaign, all in chemical engineering. His current research involves the rheology of complex fluids as well as active learning, reverse engineering online videos, and interactive textbooks.

Spreadsheets provide a user-friendly environment to complete many calculations for engineering students as well as practicing engineers. Spreadsheet programs have been available for decades, including Microsoft Excel, Google Sheets, and many others; numerous formulas, functions, and other tasks are common across versions and platforms (e.g., Windows, Mac, iOS, Android). An interactive textbook from zyBooks titled Spreadsheets Essentials provides students opportunities to step through animations, complete question sets, and perform spreadsheet functions on autograded, randomized problems. Advanced topics include solver, error, statistics, interpolation, numerical integration, matrix operations, and more. The interactive format creates 'big data' on student behaviors, such as reading completion, auto-graded problem success, and auto-graded problem attempts. Providing nominal course credit led to very high reading rates in 2018. Specifically, at least 75% of students (n=98) completed 100% of the reading participation encompassing over 250 clicks across 12 sections. In addition, animation view rates quantified repetition with rates as high as 118%. Finally, success on over 100 auto-graded questions was higher for basic skills and formulas than more advanced topics, such as integration and interpolation.