What makes a maze-based programming challenge difficult?

Computational Thinking (CT) is one of the key skills within adequate digital literacy for the 21st century. Over the last few decades, several initiatives fostered the development of CT among primary and secondary school students (e.g., The Hour of Code, CodeWeek EU, Scratch Day) using online learning platforms (e.g., Code.org). Many of the activities on these platforms are based on 2D maze-based challenges that students solve using visual code blocks. 

Our findings are based on the analysis of the platform log data gathered from 326 learners during three studies in which students were asked to solve maze-based programming challenges in our online platform, Kodetu. According to our results, a Kodetu challenge is difficult when: a) the maze has turns and the total number of steps needed to go from the initial position to the endpoint is high, and b) when not only movement blocks, but also loop and conditionals blocks are needed to solve the challenge. The results of this research should be considered when designing learning activities to develop and enhance CT skills through maze-based programming challenges.