The World Is Maths



Picture Perfect Parabolas (Desmos Activity)

I’m intrigued by the Desmos Activity Builder and where it might be useful for my students.  One of the first activities I’ve made is based on the idea of fitting graphs to photos of naturally-occurring or man-made parabolas, which I first encountered in Adrian Oldknow’s book Teaching Mathematics Using ICT back in 2004.

In my activity, students are asked to fit some parabolas to photos of bridges and fountains.  And a banana.  They are also asked to explain their thought processes before they attempt the graphical transformations. Continue reading “Picture Perfect Parabolas (Desmos Activity)”


Conic Sections (Desmos)

EDITED:  Thanks to the wonderful folk at Desmos, who helped me solve my problem within minutes of tweeting it, I now have fully functional models.  The problem was making the black dotted distance lines only point to the relevant focus/directrix and not both.  Writing lines parametrically – that’s how to impose conditions on when they appear.

I’ve been trying to make some models to show the relationship between the curve, focus and directrix on conic sections, Continue reading “Conic Sections (Desmos)”

What is ‘e’? (Desmos)

Quite simply, demonstrate the value of e using the fact that


with the sliders on this model.

Maclaurin & Taylor Series (Desmos)

Nothing original, but this model demonstrates how increasing the number of terms in a Taylor or Maclaurin series improves the approximation.  You can hide/reveal the graph of appropriate series and change the value of the pivot in the Taylor series.

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