This study surveyed 445 primary, secondary, and higher education teachers to understand their usage of AI tools in the classroom. Results revealed that while teachers generally have a positive attitude toward AI in education, only 25% of them have actually incorporated AI-based tools into their teaching. Moreover, the most common used tools were ChatGPT, Dall-E, and Midjourney. Finally, primary and secondary school teachers mainly use AI for content creation purposes such as presentations, texts, or videos, without emphasizing student engagement with AI tools. In contrast, higher education teachers utilize AI for academic-technical purposes, explaining AI functioning, obtaining information, and enabling students to experiment with AI tools, as well as research-related tasks like text translation, or data analysis. Based on these results, AI training programs for educators should be tailored to each stage, incorporating a wider variety of AI tools beyond the commonly used ones like ChatGPT.