Mystery Science (Mystery Doug) has posted their most popular science lessons and are offering them for anyone to use for free. No account or login is needed. You can sign up up for a free account to access other lessons.  All of the lessons are expertly designed to engage students, achieve learning outcomes, and be easy to use. There are short mini-lessons that are completely digital and full lessons that include an activity. All of the activities are designed to use simple supplies a parent will likely already have at home.  You don't have to stick to your grade level.  Check out any topic of interest from grades 3-5.