Introducing Trigonometry (Part 2): Welcome to 21st Century Education and the IPhone

Yesterday I described a double lesson in which my class developed a complete understanding of the sine, cosine and tangent functions for right angled triangles (see previous post). Our aim at the start of the double lesson was to figure out how high the crane outside the classroom window is and we needed new mathematics in the form of trigonometry to help us answer that question and hence a simple angle measuring device. I went home last night and made one so that the students would have a model from which they could make their own. The protractor outline was obtained from – Shape – Trigonometry – Angles of Elevation and Depression – Slide 9.


It’s quite fun to make and easy to use but horrendously inaccurate when it comes to doing what you need it to do. I wondered if there was a more accurate way to approach this? After some thought, it suddenly hit me that it would be a great idea to make an iphone app to do this! There would be the slight snag that I don’t have a clue how to make even a simple app but it would make for a cool, extended project. As with all great ideas it’s important to check that there’s nothing out there that already exists. Unfortunately for me (or perhaps fortunately), there exists such an app. Let me introduce you to the almight seelevel app.

seelevelappIt’s an absolute stunner! Once you calibrate it, it measures angles of elevation and depression, estimates the horizontal distance you are from an object and the vertical height of objects given certain information, and also happens to be a pretty decent spirit level.

It costs £0.69/$0.99 and is well worth the money.

Take a look at this picture I managed to take before our lesson.


Ensure that your line of sight, the iphone and the object are in alignment and Bob’s your uncle. Welcome to 21st Century Education!

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