The following is a list of school reference textbooks and non-fiction books sorted into their grade range.
School Reference Textbook
Pre-K and K
The Other Way is a book full of opposites, suitable for very young children or children learning to read. This is also a nice book for beginner readers, pairing the opposite adjectives or prepositions, with a related noun.
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Early Elementary
Catch a Ride on a Raindrop – The Watercycle
Catch a Ride on Raindrops is a picture book that explains all about the water cycle a very simple way, perfect for elementary school science studies in early grades.
Physics – Introduction
Physics is a little book with lots of big facts about physics. This book covers the basic principles of physics and makes a nice introduction to physics for early grades in science disciplines, and a good lead into school projects by introducing some of the facts of physics.
This book, All About Chinchillas, is an animal facts book for early grades about the adorable small rodents, suitable for children around Grade 2 level. This book is brought to us by Free Kids Books creators and is CC-BY-SA, free to share, anyhow you like.
We Love Our Home – Animal Habitats in India 
We Love Our Home is a story about animal habitats in India. This is a great nature ebook for early elementary that combines biology and geography, Have some fun looking up the animal types and the locations, make a project out of researching each species and location, there are very unique and special conservation values for each type of animal and each location – see if you can find out what they are.
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Upper Elementary
Ancient Egypt is a reference book suitable for early to mid-elementary school students, grades 1-4. This is suitable for use as a reference for projects and as a learning tool, designed to be read aloud to early grades or to be read by older grades.
Be Wise With Money is a great way to begin teaching financial literacy to children. The book explains all about money, including, the difference between need and want, staying within a budgeting, income versus expenses, different ways to pay, and even includes an example of a small business plan.
Clouds out my window is an awesome comprehensive book that explains all about clouds for upper elementary or middle-grade children in a very easy to understand way. This book was written by John Jensenius a Meteorologist with the National Weather Service, a department of National Oceanic and Atmospheric Administration in the USA.
The second book in the Happy Maths series, these books provide practical maths solutions, great for grades 5-7 with stories to help engage the students. The stories are based on Indian lifestyles which also adds to the cultural experience. Another great creative commons book from Pratham publishers.
Emotional Intelligence Activity Book 
Emotional Intelligence is a vital skill for children, often overlooked. Not only is it overlooked, but there is seldom good workbooks available aimed directly at children. This activity book is a treasure trove of wonderful exercises that get kids thinking about their own emotions, create self-esteem, empower good behaviours and habits, and develop consideration for others.
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Middle-grade
Europe is a great concise textbook for learning European geography, suitable for upper elementary and middle school. The book contains summaries of all the different countries, each summary includes history, geography, people, and sights. Along with each country’s summary the introduction includes an overview of the geography, languages, people, and the European Union.
Introduction to Biology – Wikibooks
An Introduction to Biology, a textbook for upper elementary and middle grade, published by Wikijunior, we learn about a range of topics, including a detailed look at the human body and cells, and an overview of kingdoms, archaea, bacteria, protists, fungi, plants, and animals.
Music Theory Books for middle grade
Book 1 – Music Theory Introduction for middle-grade – Pitch and Major Scales and Keys
Book 2 – Music Fundamentals 2 Rhythm and Meter – middle-grade music theory
Book 3 – Music Fundamentals 3 Minor Scales and Keys – music theory for middle grades
Music Theory Introduction for middle-grade, is an introduction to music theory, explaining the basics, first principals, in simple, easy to understand terms, suitable for middle-grade. The first three books cover major scale and keys, rhythm and meter, and minor scales and keys.
First Nation Studies Canada for upper middle-grade social studies 
BC First Nations Studies Part 1-4 covers the journeys of the First Nations of Canada, and is suitable for social studies for upper middle grade and high school The Canadian First Nations social studies textbook is licensed under Creative Commons, CC-BY-NC.
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High School
Made with Creative Commons
Made with Creative Commons shows the world how sharing can be good for business—but with a twist. Many creative commons artists are successful businesses or professionals (well paid writers, musicians, successful for-profit venture), but this is not why they do it.
Basic Book Design is a textbook suitable for high school students, Grade 9-12 (and adults) all about basic book design. The book is provided by Wikibooks, in the creative commons under a GNU open document license. As a project for English, art or computer studies, creating a book should be a compulsory activity in schools.
Rhetoric and Composition – Writing Textbook High School Extensions
This writing textbook is a perfect text for a complete guide to writing, and suitable for aspects of introductory and advanced high school English students. The book contains a complete course in writing, from writing phases, drafting, editing, types of writing, to common phrases, word types, and improved use of English sentence structure.
Bound by Law – Tales from the Public Domain
Bound by Law, tales from the Public Domain, is a comic about public domain law and fair us. The comic contains a nice exposition on how the law can be stifling to creativity and the importance of the public domain.
