The paper examines the creation and evaluation of so-called situational informatics tasks based on assembling a program from blocks. Blockly technology has enabled us to develop an environment where templates, called “worlds“, can be created. In these worlds, pupils program a certain sprite to solve a problem emerging in a described situation. We created two such templates – the world of Karel the robot and the world of Film animation, differing both in behavior of sprites and set of commands. Each template was supplied with its own set of tasks, differing in topic, subject matter and graphics. As they go through each task, pupils repeatedly run the assembled program, being provided by the system with feedback. That comprises a visual check of how the programmed sprite behaves as well as system-generated notifications reporting whether all the requirements for completing a task have been met. The tasks that were compiled for this purpose were included in the Bebras Challenge. In our paper, we describe each of the templates and look at their didactic background as well as examining findings from the practical use of these tasks in the Challenge and their inclusion in the informatics curriculum. Results show that tasks created for the world of Karel the robot used in the Bebras Challenge are no more difficult than other algorithmic tasks. Moreover, informatics teachers are impressed with these tasks and they find it of upmost importance that the curriculum includes such tasks in order to advance pupils’ informatics skills.