Constructions can be made with points, vectors, segments, lines, polygons, conic sections, inequalities, implicit polynomials and functions, all of which can be edited dynamically later. Elements can be entered and modified using mouse and touch controls, or through an input bar. GeoGebra can store variables for numbers, vectors and points, calculate derivatives and integrals of functions, and has a full complement of commands like Root or Extremum. Teachers and students can use GeoGebra as an aid in formulating and proving geometric conjectures. Anyone can use it when they need mathematics software occasionally and don’t want to install any software.

GeoGebra’s main features are:
Interactive geometry environment (2D and 3D)
Built-in spreadsheet
Built-in computer algebra system (CAS)
Built-in statistics and calculus tools
Scripting hooks
Large number of interactive learning and teaching resources at GeoGebra Materials.[8]

GeoGebra‘s source code is licensed under the GNU General Public License (GPL) and all other non-software components are under Creative Commons BY-NC-SA. GeoGebra is available on multiple platforms, with apps for desktops (Windows, macOS and Linux), tablets (Android, iPad and Windows) and web. Commercial use is subject to a special license and collaboration agreement.

Hackaday has published an in interesting series of articles on signal processing, and here are some picks from it:

RTFM: ADCs And DACs
https://hackaday.com/2019/10/16/rtfm-adcs-and-dacs/

DSP Spreadsheet: IQ Diagrams
https://hackaday.com/2019/11/15/dsp-spreadsheet-iq-diagrams/

Sensor Filters For Coders
https://hackaday.com/2019/09/06/sensor-filters-for-coders/

DSP Spreadsheet: FIR Filtering
https://hackaday.com/2019/10/03/dsp-spreadsheet-fir-filtering/

Fourier Explained: [3Blue1Brown] Style!
https://hackaday.com/2019/07/13/fourier-explained-3blue1brown-style/

DSP Spreadsheet: Frequency Mixing
https://hackaday.com/2019/11/01/dsp-spreadsheet-frequency-mixing/

Spice With A Sound Card
https://hackaday.com/2019/07/03/spice-with-a-sound-card/
- check also A real-time netlist based audio circuit plugin at https://github.com/thadeuluiz/RTspice

Reverse Engineering The Sound Blaster
https://hackaday.com/2019/06/19/reverse-engineering-the-sound-blaster/

FM Signal Detection The Pulse-Counting Way
https://hackaday.com/2019/08/28/fm-signal-detection-the-pulse-counting-way/

DSP Spreadsheet: IQ Diagrams< https://hackaday.com/2019/11/15/dsp-spreadsheet-iq-diagrams/

Here is an extra, not from Hackaday, but an interesting on-line signal processing tool for generating sounds
https://z.musictools.live/#95

Here are some slides from seminar

In 1925, Fisher published Statistical Methods for Research Workers, whete he explained the concept of statistical significance. Somewhat arbitrarily, Fisher chose to define statistical significance as a difference that had less than a .05 probability of occurring by random chance (in technical terms, this is called a p-value). 
Fast forward more than a century later, and many researchers believe Fisher’s choice of .05 has led to a crisis in science: Researches have shown that fewer than half of the published psychology findings held up when replicated and about 40% of experimental economics findings disappeared when the experiment was repeated.

What’s to be done? A new proposal is to use .005 instead for “significant” evidence. It might not solve all problems, but should help.

Some are looking at ways to “fight quantum with quantum”—but there is another (and cheaper) option.

Interesting article on mathematics of riding bicycle.

Check out these math tips and hacks.