Learning the basics of the theme "Recursion" using the "Bukashka" ("Ladybug") drawing actor software implementation

Recursion is one of the most difficult themes of the school course of informatics. The use of a drawing actor software allows schoolchildren to form a mental algorithmic scheme of the principles how recursive programs are designed and work. This will simplify the perception of more complex aspects of this theme at further stages of education. The following concepts are explained using simple illustrative examples without going beyond the limited capabilities of the learning environment: recursive call of a procedure, deferred return from the procedure, head- middle- and tail-recursion. It is shown how a WHILE and a DO-WHILE loop can be implemented using recursion. It is demonstrated how the use of recursion leads to a reduction in program size and its execution time by the example of the non-standard problem of drawing a square. Examples of problems for a graphic actor are given, solutions of which can only be designed using recursion. It shows how recursion increases the possibilities of positioning the drawing actor. It is proposed to use the drawing actor software "Bukashka" ("Ladybug") for training sessions. It is computer platform agnostic, the implementation "Kangaroo Roo" compatible and can be integrated into the information environment of an educational organization