Harmonograph A harmonograph output A harmonograph is a mechanical apparatus that employs pendulums to create a geometric image. The drawings created typically are Lissajous curves, or related drawings of greater complexity. The devices, which began to appear in the mid-19th century and peaked in popularity in the 1890s, cannot be conclusively attributed to a single person, although Hugh Blackburn, a professor of mathematics at the University of Glasgow, is commonly believed to be the official inventor.[1] A simple, so-called "lateral" harmonograph uses two pendulums to control the movement of a pen relative to a drawing surface. More complex harmonographs incorporate three or more pendulums or linked pendulums together (for example hanging one pendulum off another), or involve rotary motion in which one or more pendulums is mounted on gimbals to allow movement in any direction. Computer-generated harmonograph figure[edit] A harmonograph creates its figures using the movements of damped pendulums.
Polymaps What's Special About This Number? What's Special About This Number? If you know a distinctive fact about a number not listed here, please e-mail me. primes graphs digits sums of powers bases combinatorics powers/polygonal Fibonacci geometry repdigits algebra perfect/amicable pandigital matrices divisors games/puzzles 0 is the additive identity . 1 is the multiplicative identity . 2 is the only even prime . 3 is the number of spatial dimensions we live in. 4 is the smallest number of colors sufficient to color all planar maps. 5 is the number of Platonic solids . 6 is the smallest perfect number . 7 is the smallest number of sides of a regular polygon that is not constructible by straightedge and compass. 8 is the largest cube in the Fibonacci sequence . 9 is the maximum number of cubes that are needed to sum to any positive integer . 10 is the base of our number system. 11 is the largest known multiplicative persistence . 12 is the smallest abundant number . 13 is the number of Archimedian solids . 17 is the number of wallpaper groups .
Teaching With Infographics Earlier this week I learned from Larry Ferlazzo that The New York Times Learning Network was doing a series of posts about teaching with infographics. The last installment of the series went live today with a post by Diana Laufenberg. Diana's post includes ten steps for designing lessons in which students create infographics. Her post also includes links to some valuable information concerning the actual infographic design process. The entire Teaching With Infographics series contains a lot of very useful information for teachers who are considering using infographics in their classrooms. Infographics for Language Arts and Fine Arts can be found here, infographics for Science and Health can be found here, History and Economics infographics can be found here, and "getting started" resources can be found here. Applications for EducationI've found in my classroom that infographics can be very useful for helping students gain a better comprehension of data sets.
A First Course in Linear Algebra (A Free Textbook) Open-Source Textbooks Instead I am concentrating recommendations and examples within the undergraduate mathematics curriculum, so please visit the Open Math Curriculum page. If you are linking to this site, please use that page for a broad list, or link to linear.pugetsound.edu specifically for the Linear Algebra text. Thanks for your help publicizing open textbooks. This page contains some links to similar open-source textbooks. Free Textbooks Abstract Algebra: Theory and Applications, by Thomas W. Freedom Some thoughts on open-content, intellectual property, open-source software and books.The Economy of Ideas An essay on intellectual property, copyright and digital media. Sources of Open-Content Textbook Revolution Careful capsule descriptions of free textbooks in many disciplines. Licensing Open-Content Free Software Foundation GNU licenses, popular for software projects.
Thinkmap visualization software facilitates communication, learning, and discovery. Slide-Together Geometric Constructions This is a web version of a teacher's workshop presented at Bridges 2004Appeared in: Bridges for Teachers, Teachers for Bridges, 2004 Workshop Book, Mara Alagic and Reza Sarhangi eds., pp. 31-42. “Slide-Together” Geometric Paper Constructions George W. Hart Computer Science Dept. Abstract Seven paper construction projects provide students with experience exploring properties and relationships of two-dimensional and three-dimensional geometric figures. “Slide-togethers” based on squares, triangles, pentagons, and decagons Introduction This activity consists of seven attractive constructions which are fun and relatively easy to make because one simply cuts out paper pieces and slides them together. Each “slide-together” is made from identical copies of a single type of regular polygon (e.g., just squares or just triangles) with slits cut at the proper locations. “Slide-togethers” based on hexagons, decagrams, and pentagrams Differentiating Instruction. Copy and Cut. Cycle of Five. References
Online Mind Mapping - MindMeister