It is important to consider what an 11 to 18-year old is familiar with in terms of mathematics and logical thinking. An average 11-year old is probably learning about fractions, simple cartesian geometry, the concept of units, and mathematical expressions. By 15, the average student will be taking algebra, and hopefully will have the all-important concept of variables under his/her belt. So much in CS is dependent on solid understanding that symbols and tokens can represent abstract concepts, values, or algorithms. Without it, it's still possible to teach CS, but it must be done in a very different way (see Scratch).
Martin Burrett on 23 Nov 17"In September we introduced the new curriculum across all subjects and all of our school. This was scaffolding using the Chris Quigley's Essentials materials, during the previous year we had used a numeracy curriculum created by teachers within the Deal Learning Alliance, which a great source and piece of collaborative work in its own right, held too many links back to APP statement and old national curriculum levels. As as school we were finding that the DLA maths document did not provide the scaffold for the raised expectations in mathematics primary curriculum, furthermore, the deeper into the curriculum we delved, the harder it seemed to make the teaching, learning and assessment work efficiently."
