*Editor:* Janet Beery

*Associate Editors:* Amy Ackerberg-Hastings, Janet Barnett, Maureen Carroll, Lawrence D'Antonio, Victor Katz, Michael Molinsky, Elyn Rykken, Gabriela Sanchis, Randy Schwartz, Amy Shell-Gellasch, Jody Sorensen, Gary Stoudt, Erik R. Tou

*Founding Editors:* Victor Katz, Frank Swetz

### Articles

The Mathematical Cultures of Medieval Europe, by Victor J. Katz

Cultural influences on the mathematics of Islamic, Jewish, and Catholic scholars

Recreational Problems in Medieval Mathematics, by Victor J. Katz

Two problems that endured across time, space, and culture

Historical Reflections on Teaching Trigonometry, by David M. Bressoud

The functional approach of circle trigonometry is the historical approach!

Crossword Puzzle: Mathematical Potpourri, by Sid Kolpas and Stu Ockman

Our second puzzle from a mathematics professor and a *NY Times* crossword puzzle constructor!

Descriptions of the Integer Number Line in United States School Mathematics in the 19th Century, by Nicole M. Wessman-Enzinger

Gradual development of the now ubiquitous number line traced through textbooks of the time

A Series of Mini-projects from **TR**ansforming **I**nstruction in **U**ndergraduate **M**athematics via **P**rimary **H**istorical **S**ources, by Janet Barnett, Kathy Clark, Dominic Klyve, Jerry Lodder, Danny Otero, Nick Scoville, and Diana White

Math Origins, by Erik R. Tou

How were concepts, definitions, and theorems familiar to today's students of mathematics developed over time?

Mathematical Treasures at the Linda Hall Library, by Cynthia J. Huffman

Description of the physical and digital history of science collections of the Linda Hall Library in Kansas City. At least 75 of LHL's digitized rare books relate to the history of mathematics and can be used in classrooms.

Mathematical Treasures from the Linda Hall Library added during 2018:

Mathematical Treasures, by Frank J. Swetz

Index to Mathematical Treasures Collection: Images of historical texts and objects from libraries, museums, and individuals around the world for use in your classroom!

Mathematical Treasures added during 2018:

- Early Translation of Euclid's
*Elements* into Arabic (1466, original 9th century) (posted 02/23/18)
- The
*Trevelyon Miscellany* (1608) (posted 02/11/18)
- Jean Prestet's
*New Elements of Mathematics *(1694) (posted 02/12/18)
- Lamy's
*Mathematical Works* (1734) (posted 02/10/18)
- Müller's
*Elements of Mathematics* (1765, original 1748) (posted 02/22/18)
- Langsdorf on
*Kaestner's Analysis of Finite Quantities* (1776-1777) (posted 02/09/18)
- Maria Agnesi’s
*Analytical Institutions* (1801)
- Ludlam's
*Rudiments of Mathematics* (1809, original 1785) (posted 02/20/18)
- Simpson's
*A Treatise of Algebra* (1826, original 1745)
- Robert Simson's
*Elements of Euclid* (1834, original 1756)
- De Morgan's
*Elements of Trigonometry and Trigonometrical Analysis* (1837)
- Potts's
*Elements of Euclid* (1871, original 1845) (posted 02/15/18)
- Peirce's
*Linear Associative Algebra* (1882)
- Two Works of Heinrich Weber (1891 and 1895)
- Forsyth's Complex Variables Text (1893) (posted 02/16/18)
- Burkhardt on Analytic Functions (1897)
- Wilson's
*Solid Geometry and Conic Sections* (1908, original 1872) (posted 02/21/18)
- Hobson's
*Theory of Functions of a Real Variable* (1921, original 1907) (posted 02/14/18)
- Hardy's
*A Course in Pure Mathematics* (1921, original 1908)
- Lamb's
*An Elementary Course of Infinitesimal Calculus* (1934, original 1897) (posted 02/13/18)