Based on your search query, I believe Whimsical would be an excellent choice for facilitating brainstorming sessions.

Whimsical is a digital workspace that offers a range of tools such as flowcharts, wireframes, mind maps, and sticky notes. These tools can help you create engaging, visual content for your lessons and promote real-time collaboration among your students.

Here are some key features that make Whimsical a great fit for your needs:

• Boards: These provide an infinite canvas for visual thinking, allowing you to visually represent complex ideas and concepts.
• Docs: This feature is ideal for combining written and visual content in an engaging, easy-to-read document-style format.
• Collaborative Work: Whimsical supports collaborative work, making it an excellent tool for group projects or team-based activities in the classroom.
• AI-powered suggestions for Mind Maps: This feature helps users generate new ideas instantly, aiding in overcoming mental blocks during brainstorming sessions.
• Text-to-Flowchart feature: This tool allows users to translate their ideas into flowcharts in seconds, which can be particularly useful during brainstorming sessions.

Moreover, Whimsical offers an education plan that allows teachers and students to use the platform free of charge, making it a cost-effective tool for educational institutions.