I have recently written a unit for year 7, to transition them from block coding to text-based coding in Python. In years 8-9, I continue this somewhat by using block coding as my algorithm designer. Here, students can design their solution, test it and then refine it to make it more efficient. For example, instead of a series of sequenced commands that repeat, students can get the sequence working and then refine the algorithm with loops; and then test it again. I find the drag and drop nature of block coding to be a better environment for prototyping because you can work on several iterations of a design quite quickly and its a more visual experience as well. In particular, its probably a superior environment for beginning with embedded systems, such as the BBC Micro:bit or The Circuit Playground Express. In fact, these environments have a text coding view as well; facilitating the transition to text-based coding.
In this unit, I introduce students to python via turtle graphics. Here is my Unit; enjoy!The-Art-of-Code-2D