All in One Homeschool - A free, online homeschool curriculum developed by one family. This curriculum is Christian-based and has materials for Preschool through 8th grade. A separate high school site is available as well (listed below).
All in One High School - Partner website to All in One Homeschool, with materials for high school.
Khan Academy - A nonprofit website "with the mission to provide a free, world-class education for anyone, anywhere." KA has a variety of classes to choose from, and all materials are free and accessible with an account.
Online Homeschooling Resources Compilation – This website provides a starting point for homeschooling, from parents.com, that goes through many of the important questions you'll need to answer before starting to homeschool. This compilation is split up into different sections, and provides resources for each, such as educational philosophies, legal requirements, online curriculums, online learning websites, blogs, and online communities (Facebook and Twitter). The material may be a little dated (the article was written in 2012), but it is a nice outline of topics for those who are new to homeschooling to start considering.
How Do I Homeschool? - This blog is another starting point for people who are trying to decide if they want to homeschool or not. This article lists out each step and topic that needs to be considered for homeschooling, and provides links. The author of this blog is Christian and includes personal examples that feature her faith. Other information that she provides is more general.
Home School Legal Defense Association - HSLDA is a nonprofit that works to "defend and advance the constitutional rights of parents to direct the education of their children and to protect family freedoms." Through HSLDA, you can join as a member and have a low-cost method of obtaining quality legal defense. While the founding members of HSLDA seem to be Christian, there is no requirement for members to be Christians, or to use Christian curricula.
All About Learning Press - All About Learning Press has two homeschool curricula available for purchase - All About Reading, and All About Spelling. The founder of All About Learning Press, Marie Rippel, started this program in response to her son's diagnosis of severe dyslexia, and features multisensory programs and scaffolding.
Timberdoodle Co - This is a website where you can get educational materials from at discounted prices. Materials range from books, props, toys, models, DVDs, etc
Montana Coalition of Home Educators - The MCHE's goals are to "bring homeschoolers together to protect Montana's home school freedom, while maintaining the independence and autonomy of the individual families and the existing local and state organizations." They have a very informative FAQ about homeschooling in Montana, and their "Support Group" tab has a helpful list of all homeschooling groups and organizations in the state. if you are looking to connect with someone in your area to ask questions about homeschooling, this website is a good resource for that.
OPI Home School Informational Packet (PDF) - OPI has put together this document that outlines key statutes regarding private/nonpublic schools in Montana, as well as rules and statutes regarding homeschooling. It also provides links to the 2017 Montana Annotated Code if you would like to read more in-depth into the rules and regulations.