The internet is brimming over with Science related materials - on almost any topic and at most levels. Planning a path for students to follow will help to direct their activities and enhance the learning that takes place. Most internet science resources are NOT aimed at a school based audience. Resources that are directly suitable for use in the Science laboratory are few and far between.
Most resources are be more likely to be used in investigations, report writing etc.
These lists are not intended to be exhaustive - they cannot be through the nature of the internet. They will provide some starting points and ideas - and will be good sites to start investigating. Click a subject for more specific sites, or scroll down the page for some general science resources. The site has a wide range of information for members and non-members. The US equivalent of our own ASE - again with a wide range of science teacher resources and information.