Exploratory testing provides an intuitive way for testing a software product that testers can apply, but the advantages of exploratory testing are generally outweighed by its disadvantages, mainly the time and resources necessary to perform it manually. To address this problem, in this research, we propose Model-Based Exploratory Testing (MBET), an approach that incorporates the advantages of exploratory testing and Model-Based Testing (MBT) that automates the testing processes. To support the MBET approach, we implemented an automated testing tool, the Crushinator. To assess our approach, we conducted an experiment using an educational game application with multiple versions and we collected the number and type of defects detected with the MBET and MBT approaches. Our results showed that, overall, MBET detected more defects than MBT. The results also showed that MBET detected certain defect types better than MBT while MBT detected other types better than MBET.