This activity , I have found to be very enjoyable for pupils, because it opens up a new world for most of them - that they can create their own number patterns and explore them! It's a healthy change for many of them to feel that they are not just being handed something that the teacher already knows an awful lot about. So if these thoughts encourage you then present it to your pupils.
The patterns that are generated can be very exciting. I find it useful if the children have already met things like the patterns that are evident in the ninetimes table to take things a bit go further and investigate Digital Roots. I have also found that following the a, b, c, d, e parts as suggested in this activity, writing what they notice, changing something slightly and repeating etc. to be a very good investigational process for the youngsters to get used to. Caleb Gattegno in the 1960's said; "Mathematics is the study of the invariances under a set of transformation". Or if you prefer it, in my words now; "Doing mathematics is taking something, changing it in some way and observing what is the same and what is different."