Science Snacks from Exploratorium is a great collection of hands-on science lessons for elementary school, middle school, and high school students. I've been recommending it for years and recently revisited it to discover that more activities have been added.
Science Snacks features activities that can be
conducted with inexpensive and readily available materials. Each Science
Snack comes with a materials list and step-by-step directions. Science
Snacks are also accompanied by a written explanation of the science at
work in the activity. Many Science Snacks, like Penny Battery, include video demonstrations and explanations.
You can search for Science Snacks alphabetically or you can search by subject.
The subject search is the best way to search if you are looking for an
activity to match a lesson plan or curriculum standard that you already
have in mind.
Applications for Education
Many of the Science Snacks activities could be
conducted by students at home with the
help/ supervision of parents. Using the Science Snacks in that way could
be a good alternative to typical homework assignments. Have students do
one of the activities for homework and report their observations in
Google Documents or as comments in Google Classroom.