The University of Colorado - Boulder has been working hard to create education interactive software which is free to all users. Specializing in Physical Sciences, this site has great tools for Newton's Laws, Gravity, Inertia, Momentum, Atoms, Molecules, Physical and Chemical Reactions and many other important laws! Many of the modules have already been updated to HTML5 and can be used on any newer device. The older modules that have not been updated yet will still require Java and Flash, so they will not work on any Apple products, or most tablets and Chromebooks.
For many years now, children have grown up with PBS educational programming and they have brought their knowledge and programming online! You can search for whichever type of media you need, but the interactives and videos are a highlight of this site. The interactives cover a broad range of topics including tons about whether and climate, how the Earth works, how many animals and their habitats function and even light and color. These modules will require flash (and possibly Java) to run.
The British Broadcasting Company is kind of like England's version of PBS. They have plenty of education programming and have added materials online. The have some really good tutorial videos that will pause when you need to interact with them. Since their school levels are labelled differently, look for KS3 (ages 11-14) which is essentially middle school in the United States.
Though a bit simplistic, these interactive games teach about a variety of physical science topics like states of matter, electricity, magnetism, light and forces; as well as life science topics like bones, plant growth and food chains. These modules will require flash (and possibly Java) to run.