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. A simple, so-called "lateral" harmonograph uses two pendulums to control the movement of a pen relative to a drawing surface. One pendulum moves the pen back and forth along one axis, and the other pendulum moves the drawing surface back and forth along a perpendicular axis. By varying the frequency and phase of the pendulums relative to one another, different patterns are created. Even a simple harmonograph as described can create ellipses, spirals, figure eights and other Lissajous figures. 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. A particular type of harmonograph, a pintograph, is based on the relative motion of two rotating disks, as illustrated in the links below (as opposed to a pantograph, a mechanical device used to enlarge figures). (Wikipedia).
Writing Equivalent Polar Coordinates Quiz
Link: https://www.geogebra.org/m/MxAvq5Yt
From playlist Trigonometry: Dynamic Interactives!
Adding Vectors Geometrically: Dynamic Illustration
Link: https://www.geogebra.org/m/tsBer5An
From playlist Trigonometry: Dynamic Interactives!
A very quick demo of how to access the 2D and 3D calculator on Geogebra.
From playlist Geogebra
How Pythagoras Broke Music (and how we kind of fixed it)
How does music work? What did an Ancient Greek philosopher have to do with it? Why did he keep drowning people? Discover the answers to these questions and more as we take a tour through musical tuning systems, examining how the power of mathematics has helped us build and rebuild our met
From playlist Mathematics
The Big Summer Science Quiz 2020 | The Royal Society
Comedian Steve Cross hosts the perfect science quiz for all ages, with special guests Brian Cox, Maggie Aderin-Pocock, Konnie Huq, Adam Rutherford and Martyn Poliakoff. Opening music: bensound.com The Royal Society is a Fellowship of many of the world's most eminent scientists and is the
From playlist Summer Science 2020 on demand
How to Create a GeoGebra Class from an Activity
More info: https://www.geogebra.org/m/hncrgruu#material/mxc255j6 #GeoGebra
From playlist GeoGebra Classroom: Quick Tutorials
Introduction to Geometer's Sketchpad: Measurements
This video demonstrates some of the measurement and calculation features of Geometer's Sketchpad.
From playlist Geometer's Sketchpad
Constructing a REGULAR POLYGON: GeoGebra Beginner Exercise 1
Screencast displays how to use the REGULAR POLYGON tool to construct various regular polygons in GeoGebra. Try it yourself here: https://www.geogebra.org/m/NUtDnGgC#material/ez3tzHra
From playlist GeoGebra Geometry & Graphing Calculator: BEGINNER Tutorial Series
Messing with Mona: Introduction to Geometric Transformations
Link: https://www.geogebra.org/m/KFtdRvyv
From playlist Geometry: Dynamic Interactives!
Finding EXACT Trig Ratios: Quiz Question Generator (with Feedback)
GeoGebra Resource Link: https://www.geogebra.org/m/mnzckzbv
From playlist Trigonometry: Dynamic Interactives!
Cindy Lawrence - Playing with Math: Squares and Cubes - CoM Aug 2021
Meet Cindy Lawrence, one of the original founders of MoMath and its current Executive Director and CEO, and join her in an exploration of squares and cubes, MoMath-style. What surprises might these simple shapes hold? Hear the story of how three squares attracted three thousand people an
From playlist Celebration of Mind 2021
Composing Trig & Inverse Trig Functions (1)
Create a #GeoGebra lesson out of https://www.geogebra.org/m/byevwtd8 , have remote & in-class Ss join, & observe everyone’s thinking in real time! Here, evaluating compositions of #trig & inverse trig functions: https://www.geogebra.org/m/ezkfbxsu
From playlist Trigonometry: Dynamic Interactives!