Abstract: We introduce a newly developed visual programming and UML modeling tool for educational use. It’s implemented to provide students with informative feedback during exercises as well as to assess the submissions of students automatically. Tasks combine class and activity modeling aspects as well as some simple programming requirements. The system is web-based and named COCLAC. Visual programming is done through an included UML editor. Created diagrams are syntactically checked and automatically converted into Java code using several conventions. Thereafter, code is executable on a server and semantic correctness can be checked through automatic tests.