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Review: How Far Away Is It?

Robert Prior, ePublisher OAPT Newsletter

There’s a lot of good physics (and math) embedded in the grade nine space unit, if you know where to look for it. David Butler is a retired computer scientist who is fascinated with space, and he’s applied his mathematical background to explaining, in simple terms, what’s behind the fancy pictures we see from NASA, and how we know what we know about the universe. To do this he’s created a series of video books focusing on different topics, as well as hundreds of short classroom-ready video clips on topics ranging from astronomy to quantum mechanics.

David Butler is not competing with Carl Sagan or Brian Cox — he is concentrating on answering a specific question: how do we know how far away/small/fast/old that is? In his own words:

His website is well-organized, easy to navigate, and has clearly grown beyond the original project!

Video Books

Butler has created four video books, each one focused on a specific question.
Each book (series of videos) starts with a preface, and ends with credits including links to the research used and ideas for further exploration.

The videos aren’t dramatic and don’t have dazzling special effects — if you seek something to entertain a bored class these are not the videos you’re looking for. What you get is a kindly grandfather explaining in a gentle voice something that fascinates him.

I was happy to see that Butler includes good historical references, such as noting that the first known mention of negative numbers was in the book 九章算术 (The Nine Chapters on the Mathematical Art) written before 100 BCE.

The videos (and associated resources) are released under an Attribution-NonCommercial-ShareAlike 3.0 licence.

How Far Away Is It? was David Butler’s first video book, and is the most extensive. It includes a PDF file with a transcript of every video in the book.

Starting in his back yard, Butler works through four concepts:
  • triangulation (measuring the earth)
  • parallax (measuring the solar system)
  • luminosity (measuring the galaxy)
  • red-shift (measuring the universe)
The first two are mathematics, but the last two are physics concepts that students will encounter later: the inverse-square law and the Doppler effect. There is no harm in emphasizing to our students that they are learning physics, even if the unit is labelled as space science!

The book is divided into chapters, each of which has multiple video segments:
  • the solar system
  • the milky way
  • galaxies
The other video books focus on different (if related) questions. They are the same style, starting in Butler’s back yard at a human scale and developing upon the concepts we need in order to answer the question the book focuses on.

Classroom Aids

Sometimes a teacher only needs part of a video to explain or illustrate a specific point. All the video books have been broken down into short subject-oriented components with no background music.
These videos are ideal for embedding in a presentation or lesson.


Each video in the video book had a transcript with text, notes, and equations. All of them are gathered in one place so they can easily be reviewed.

Lesson Plans

This is the most underwhelming part of the site. I was originally excited to see two dozen lesson plans, but most are simply “watch the video and take this short quiz”. They are provided in both PDF and DOC format, so you can edit the quizzes if you like (or incorporate them into other assessments).

Curriculum Links

Depending on the depth you want explore, Butler’s videos can be used for the following expectations:
  • SNC1D: D2.1, D2.3, D2.5, D3.1, D3.2, D3.4
  • SPH3U: D3.9, D3.10, D3.11
  • SPH4U: F1.1, F2.1, F2.2, F2.3, F3.1, F3.2, F3.3, F3.4
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