Sometimes 'Compression' Makes things Worse

It turns out that we can use 'run length encoding' to compress things (it actually work best with numbers and text). An easy way to explain the concept is to get kids to compress black and white images (as shown in the cartoon below). One thing that they sometimes find surprising is that when compressing, there will pretty much always be cases where 'compressing' makes things worse. The key idea my students need to 'get' is that they should choose compression methods carefully so that this does not happen. I would not teach it quite this way but it makes for a fun cartoon.