Introducing Standard Form: How fast do the planets move?

An interesting way to introduce standard form is for it to naturally arise out of an activity which involves large numbers. A good example of this is through an investigation as to how fast the planets move.

Whilst trying to calculate the speed of some of the planets, some of the students got confused by the calculator display:  “What does 2.7E10 mean on the calculator?”

This initated a discussion as to the relevance of standard form.We went on to plot the relationship between the orbital radius and the speed of each planet on Geogebra. It turns out to be a nice example of an inverse relationship which can be re-visited later on in the course. The curve is shown below with distance from Sun (km) on the x-axis and speed (km/h) on the y-axis.

I got all the info (with the answer sheet) from this great website:

Resources – Lesson PowerPoint, Answers.


I recently read a post written by Hannah Radders on her blog, ideasfortheclassrooom, about a planet investigation she did with her year 9 set. Starting with the speed of the planets and then moving onto creating a scale for the distances and masses of the planets would be a great project! Click the link to see her excellent idea for the classroom – Standard Form and the Planets.

This entry was posted in Functions, Investigations, Shape and Measures and tagged , , . Bookmark the permalink.

One Response to Introducing Standard Form: How fast do the planets move?

  1. Thank you Dan! That’s an excellent site and a really good idea.

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