Subject: Physics/Maths/Biology/Chemistry
Level: GCSE/A Level primarily, but also some use at KS3
Link: https://phet.colorado.edu/en/simulations/filter?type=html
The Colorado Edu Phet Simulations are a great way for students to be able to explore science in action. They can be used to replace practicals that cannot be conducted in school, either due to a lack of resources, safety, or feasibility. They are an amazing resource for students to study practicals at home for practical theory exams, and also an amazing resource for international schools that may not have the same access to experimental supplies for schools.
The simulations vary and should be checked out in advance, but many of them allow students to conduct full experiments, while others allow students to see real-time visualisations of scientific phenomena that cannot be observed by eye. I know this is a well know resource, but it is such a valuable one I wanted to include it here!