Elementary science through high school specific subjects
Science naturally encompasses a huge variety of topics, from the traditional subjects to "how things work". There is no right order to study them. Public schools tend to cover the same standard topics but homeschooling is a great way to break out of that box!
Younger Grades
Generally for lower grades (K-5), students switch between multiple topics, learning a little bit about a lot of things. Use the library liberally, reading or watching videos about whatever your child is interested in. Add in hands-on activities from any number of books or online science project lists. Unit studies can be a nice way to work in some science, writing and art skills, and math too. Some people find it's useful to have a "spine" curriculum, such as a textbook, and use it as a guide, adding to it your own side projects or reading.
Upper Grades
Once in middle and high school you may want to stay on a certain topic for more in-depth study. Spend a few months or the whole year on Chemistry, Physics, Biology, Astronomy, Earth Science, etc. Frequently middle school students in public school get shortchanged on these subjects, but there is no reason your 6th grader can't do a longer unit on physics or chemistry etc.
Take advantage of your child's interests, there is no "right" list of topics (unless your high schooler needs to pass tests for college). Rabbit-hole investigations can be very rewarding, such as combustion engines or volcanoes, or subjects can be taken in a less traditional direction, such as environmental biology, or forensic science. At this level, especially high school, the student's needs may exceed your background, and there are lots of online classes to help with that.
Real Science Odyssey - High quality and comprehensive text/workbooks, by subject. Level 1 is for elementary grades, and includes Life Science, Earth and Environment, Physics and Chemistry. Level 2 is middle school reading level but much more comprehensive than the average public school middle books. Currently, Biology and Astronomy are available for level 2, others are in the works. The books have integrated text lessons and workbook pages, with separate teachers manuals.
Oak Meadow Science - For grades 5 - 12, you can purchase the Oak Meadow science books separately from the rest of the curriculum. These cover different topics in each grade level book, so check the table of contents in the sample files to see which topics you would like to cover. Generally a more holistic, less STEM approach.
Building Foundations of Scientific Understanding - (BFSU) - Academically rigorous, comprehensive science curriculum, written and self-published by a teacher. Books are directed to the parent/teacher on how to explain the concepts, rather than reading for the children. Volumes 1 - 3 cover grades K-8. Print copies on Amazon or download from the publisher's site inexpensively.
The Story of Science books - Three volumes by historian Joy Hakim, written to a middle school level in an interesting, engaging way, covering the people in scientific history and their discoveries. An excellent study for those who want to hear the why's and how's of science, or as a supplement while studying topics elsewhere. Study guides available. Also, Build Your Library Grade 8 curriculum includes a study path using these books.
Mystery Science - Great for K-5 ages! Web site with 15-minute video lessons on many topics, with an optional activity at the end. Each video starts with a question, then works through finding the answer. Subscription based but they offer an initial free year.
Outschool - The Outschool platform offers online classes by independent teachers, some one-day workshops, some a few weeks, others a full semester. Use a web cam and microphone to interact with other students. Pay for each class individually. Huge variety of topics!
Middle School Chemistry -Full year of middle school age chemistry. High quality and completely free! Includes lessons with reading passages, animations, printable student reading and questions, lab sheets, and quizzes.
Conceptual Science - Full year upper middle and high school level science courses. You purchase the textbook separately (Amazon, et. al.) and they provide a complete lesson plan, hundreds of videos that track with the textbook, labs, quizzes, assignments, etc. Chemistry, Physics, Biology, Astronomy and Physical Science.
Physics Classroom - Online and free, comprehensive physics study at a high school level. Lessons and interactive demonstrations of many physics concepts. Activity sheets, review questions and quizzes available.
Visual Learning Systems - Online subscription or DVD based videos, with teacher's guide that include review questions and activities. Grades 5-9, all standard science topics. Homeschool pricing available.
FundaFunda Academy - Online high school Biology and Ecology classes with recorded teacher videos and a teacher who grades homework and communicates with students via message board or email. Tuition based, register in Spring for semester classes.
Derek Owens - Although Derek Owens teaches mostly high school math, he offers one Physical Science class. This is online, in a video format, aimed at 8th or 9th grade, and covers and Introduction to Physics, Chemistry, and some Earth Science. Subscription based, for as long as you need to finish the class.
Mr. Q Science - Life Science, Earth Science, Chemistry and Physics for middle grades. Written by a former teacher, the downloadable texts are chatty and full of humor.
Thinkwell - Online high school science, mostly honors Chemistry, Physics, Biology and also Economics. Videos and practice problems, automatically graded. Purchase a course and have access to it for one year. Also high school math.
Next Level Homeschool - Online courses with prepared, narrated slides and videos, and teacher and peer interaction through the discussion boards. Science offerings include Biology, Marine Biology, and Genetics. Age range 10-17 (fast paced classes).
PHET Interactive Classroom - High school level online simulations for Physics, Chemistry, Biology, Earth Science, and math. These are great supplements to understanding equations and relationships in a visual way.
Clover Valley Chemistry - High school level online classes with teacher support. Regular and honors Chem, Organic Chem, Bio Chem.
Crash Courses - Lively, fast-paced videos online for many high school level science subjects, all free. The video hosts speak very quickly but if you change the speed setting to 75% they are easier to comprehend. Include Biology, Ecology, Anatomy, Chemistry and Physics. Great for supplementing your program with interesting videos.
Blue Tent - Online courses for high school, in English, Science and Math. Fairly expensive, but all inclusive, no planning involved.
The Great Courses - This provider of adult learning courses also has some at the high school level. This chemistry course includes 36 lectures and a 180 page downloadable course materials file. They are frequently on sale for 50% off.
Tyler DeWitt Videos - Middle and high school level Chemistry videos, and some really cool Virtual Reality videos inside a cell!
CK-12 - Free, online course materials (reading, videos, quizzes) in all sciences, for all grades. A good resource especially for middle and high schoolers.
Brilliant.org - Free, online problem solving lessons and interactives for high school level science, engineering and math.
Bozeman Science - Online videos for high school AP level Physics, Biology, Chemistry and Env. Science. Good for random access or for studying for those AP exams.
WindWise Wind Energy Curriculum - High school level, free 19 downloadable lessons with supplemental activities and videos on wind energy production.
The Home Scientist - Affordable high school science kits for independent learners. Biology, Chemistry and Forensic kits include downloadable lab instructions.
Home Science Tools - Science supplies and kits, including teacher resources and homeschool kits.
Carolina Biological Supply - Especially for life science, preserved specimens and dissection kits.
VWR Lab Equipment and Supplies - Professional and educational lab supplies
Fisher Scientific - Professional and educational lab supplies
MEL Science Kits - Monthly chemistry experiment kits mailed to your home, with instructions and VR app options.
Most public school science textbooks are easily adapted to homeschool and provide a good "spine" reference to build your own study plan. The downside is that on the publisher's web sites it may not be clear how to obtain a single copy of the book, preview the Table of Contents, or view sample lessons. The upside is that they are all available "used" on Amazon or elsewhere, so for a lesser dollar amount, you can afford to order them without the high price tag. Also check with publishers for "homeschool pricing".
When looking for additional activities to go along with the textbook reading, try online sources such as TeachersPayTeachers, or search on Google, such as "High school chemistry worksheets".
Harcourt Science - Popular in the past, not in print now but lots on Amazon.
Science Fusion - by Houghton Mifflin Harcourt
Interactive Science - by Pearson.
Science Explorer series - by Prentiss Hall.
Holt Science and Technology - One of the few publishers that has a specific Homeschool package.
Holt-McDougal Homeschool science packages: Biology, Chemistry, Earth Science, Physics. If you order through the Homeschool Buyers Co-Op you get the textbook plus online access to resources such as simulated labs, videos, etc.
Introductory Chemistry: An Active Learning Approach, by Marc Cracolice - The perfect book for kids who want high school chemistry but are not going into science in college
World of Chemistry, by Steven Zumdahl
Holt Modern Chemistry - Teacher edition, solution guide and online resources available used on Amazon, or via the Holt homeschool package (see above).
Conceptual Chemistry, John Suchocki - Text book and online live teacher videos on their free web site corresponding to every lesson in the book.
Conceptual Physics: The High School Physics Program, by Paul Hewitt, classic textbook in it's 12th edition. This is introductory high school level. There are free videos for every lesson in every chapter on his web site! ConceptualAcademy.com.
Glencoe Physics: Principals and Problems, McGraw-Hill publisher. Standard high school physics textbook, student and teachers editions available used on Amazon.
Holt Physics homeschool package (see above)
Miller and Levine Biology - High school biology textbooks, print or now online format for iPads. Teacher edition available. "Dragonfly" is the older edition, "Macaw" is the newer edition.
Holt Biology homeschool package (see above)
Glencoe Biology - Standard high school biology textbook, student and teachers editions available used on Amazon.
Life On Earth, Edward Wilson, E.W. Wilson Biodiversity Foundation - A free electronic textbook only available for iPad, but it covers high school level, modern science of animal and plant physiology, cells, genetics and biodiversity.
Holt Earth Science - Individual textbook or teacher's edition used on Amazon, or through the homeschool buyers co-op (see above).
Holt McDougal Environmental Science - Individual textbook or teacher's edition used on Amazon, or through the homeschool buyers co-op (see above).
Glencoe Earth Science: Geology, The Environment and the Universe - Standard high school earth science textbook, student and teachers editions available used on Amazon.
Oregon Homeschool Science Club- A group run by Jilene Modlin, homeschool mom and teacher, offering a large variety of science classes at OMSI every Tuesday, for ages K -12. Chemistry labs, Biology lab, Physics, Astronomy, middle school challenge, and more. Sign up in the Spring for annual sessions starting in October.
Other sources for science lab classes are:
Community college - for those over 16 generally
Village Home - This co-op offers a varying selection of science courses for elementary through high school
Some homeschool charters offer in-person classes, if you join the school. Alliance Charter Academy, Clackamas Web Academy, and others.