I've yet to find a book that introduces sight reading as smoothly as this book. Do keep in mind that this book is designed for the student that knows nothing about reading notes. A student that knows beginner level basics might not find the material to be challenging enough.
"I Can Read" separates pitch reading from rhythm reading which is absolutely brilliant since they really are two completely different skill sets. This separation of skills makes this sight reading book perfect in the Suzuki Method setting but could really be used with any teaching approach.
Because the concepts are so simple, there's a high probability that any at-home sight reading assignments will be done correctly. This is advantageous when the student is young and the parent is not musical themselves. The less confusion, the better.
This book is definitely worth checking out if you teach beginner students of any age.