spoken english /Communicative english books for 6 years- 16 years

I am looking for an experienced freelancer to develop a series of spoken and communicative English books for children aged 6 to 16 years old. I am open to any topics, as long as they are suitable for children and engaging enough to keep them interested. Each book should be around 50-100 pages. If you have prior experience in developing and writing books for children of this age range, I’d love to hear from you. Please provide examples of your previous work if possible.