Hex colours are all the ways you can combine the 3 primary colours of light, red, green and blue, as a 6-digit number. There are 16 million possibilities. e.g In the number #123456, 12 is a shade of Red, 34 is a shade of Green, and 56 is a shade of Blue. You can see how changing each digit effects the final colour at quite a few internet sites such as this one:

Some people have used this idea creatively. You know we can write the time of day as a 6-digit number. The first two digits are the hour in 24-hour time from 00 to 23. The next two digits are the minutes from 00 to 59. The last two digits are the seconds from 00 to 59. For example 13: 09: 22 is 9 minutes and 22 seconds past 1 o’clock in the afternoon.

Using this information, you can now go to a website that shows what colour these 6 digits represent on the HEX Colour system. They give a specific colour for every second of our 24 hour day. That’s just 86 400 out of the possible 16 million possible colours.

What else can your students do with this system?