The Lukeion Project – language arts online coursework
Our first online class was with Natural Math and my daughter loved it as a 6th grader.
Acellus – online option for $30 a month, all subjects. My 8 year old in particular likes this one. Several homeschool families we know use this option for much of their learning. The classes are hit or miss, but it’s a good option for covering core subjects if you’re traveling for a few months.
Aleks math – used by schools in at least 2 districts in another state where I used to teach.
Life of Fred – the books are often prices best on this page of Educents. It helps if the kids know some of the story from the earlier books before diving into the Pre-Algebra books – Pre-Algebra with Biology, Physics, or Economics.
Physics for 6th grade – part of the Life of Fred Pre-Algebra Series
Tools and methods
Forces, speed, velocity and acceleration
Energy and energy transfers
Simple machines and mechanical advantage
Waves and light
We love the Gilder Lehrman Institute for American History. You can spend a 15-30 minute period on any time in American history and really learn some interesting tidbits.