Several models of Continuous Professional Development (CPD) have been shown to meet the criteria of scalability and fidelity. Here are a few examples:

1. Online Platforms and Courses: Online CPD platforms offer scalable solutions that can reach a wide audience of educators while maintaining fidelity to content and pedagogical principles. Platforms like Coursera, edX, and Khan Academy provide courses and resources that educators can access flexibly, allowing for scalability without compromising quality.

2. Blended Learning Approaches: Blended learning combines face-to-face instruction with online components, offering scalability by leveraging technology while maintaining fidelity to traditional instructional methods. This model allows for personalized learning experiences and ongoing support while reaching a larger number of educators.

3. Peer Learning Communities: Professional learning communities (PLCs) and peer networks provide opportunities for educators to collaborate, share best practices, and engage in reflective dialogue. These communities can scale effectively by utilizing digital platforms for communication and resource sharing while maintaining fidelity to the collaborative learning process.

4. Train-the-Trainer Models:Train-the-trainer programs empower educators to become facilitators of professional development within their schools or districts. This model ensures scalability by building capacity within the educator workforce to deliver high-quality training while maintaining fidelity to established content and instructional practices.

5. Microlearning and Just-in-Time Support: Microlearning involves delivering content in small, manageable chunks, making it easier to scale and integrate into educators' busy schedules. Just-in-time support provides timely resources and assistance when educators need them most, ensuring fidelity to addressing immediate needs while maintaining scalability across diverse contexts.

6. Data-Driven Professional Development: Using data analytics and evidence-based practices, CPD models can tailor professional learning experiences to meet educators' specific needs and preferences. By leveraging technology and data, scalable CPD programs can provide personalized support while maintaining fidelity to research-based strategies and outcomes.

These models demonstrate how CPD can be designed to achieve scalability and fidelity, ensuring that educators have access to high-quality professional learning opportunities that meet their needs and support continuous growth and improvement.