Barnaparichay Part 1 is the famous primer Ishwar Chandra Vidyasagar wrote in 1855 to teach Bengali children their letters. Few books in any Indian language have shaped how an entire population first learns to read. The structure is simple, the lessons are short, and the alphabet builds in careful steps.
For historical and cultural reasons alone this book is worth knowing. For Bengali children, it is also still a useful first reader.