A library of interactive science and math simulations covering physics, chemistry, biology, earth science and math. The maker describes them as free and research-based. The simulations are built in HTML5 and can be run online or downloaded, and there are translations and mobile apps.
The site says sponsors keep the simulations free for students and teachers.
Watch for The pages we read give no grade range for the simulations, so try each one yourself before assigning it to younger children.
Visit PhET Interactive Simulations ↗ Facts read on the maker’s page.
NASA's science site for kids, with sections on Earth, the Sun, the Solar System and the Universe. It has games, crafts, activities, videos and a glossary, a Spanish version, and a menu for parents and educators. One listed game has children use antennas to talk to spacecraft.
The pages we read show no price, account or sign-in.
Watch for The pages we read do not give ages or grades, so read an article first to judge the reading level for your class.
Visit NASA Space Place ↗
33. NASA Science for Kids
NASA
A NASA kids hub for Earth and space science built around four sections: Play, Watch, Make and Read. It lists games such as an ocean-currents game and a CubeSat builder, short videos on weather and climate, and articles on clouds and the carbon cycle. It also points to other NASA kid sites, including Space Place.
The pages we read show no price, account or sign-in.
Watch for The page gives no ages or grades, and the Make section listed no specific activities when we looked.
Visit NASA Science for Kids ↗
44. Exploratorium Science Snacks
Exploratorium
Hands-on science activities from a San Francisco science museum, made with common, inexpensive materials. You can search by subject, science standard (NGSS) and grade band, and there is a Spanish collection. The museum says most can be built in under an hour.
The pages we read show no price or account.
Watch for The About page says the Snacks were first written for secondary teachers and now cover grades 6-12, though elementary teachers use them with changes, so younger classes need adapting.
Visit Exploratorium Science Snacks ↗ Facts read on the maker’s page.
A full science curriculum written by researchers and educators, with units for elementary, middle and high school. The site lists the download price as $0 and describes its Self-Guided Learning Paths as free. High school courses are described as rated all green by EdReports.
Free to download: the site lists the download at $0 (as of 2026-10-27).
Watch for It is a whole curriculum rather than a drop-in activity, and the site has Login, Register and Purchase options we did not explore, so read the terms for what you need.
Visit OpenSciEd ↗
66. Ask A Biologist
Arizona State University
A biology site from Arizona State University with stories, games, activities, videos and a podcast. It also has coloring pages, a virtual microscope, a bird finder and a Teacher Toolbox section.
The pages we read show no price and ask visitors for donations.
Watch for The home page has a Sign In link and does not explain what it is for, and it does not give grade levels, so check a lesson before using it.
Visit Ask A Biologist ↗
77. Khan Academy
Khan Academy
A nonprofit whose stated mission is a free education for anyone, anywhere. It lists science among its subjects, within more than 840 courses for K-12 and early college.
The About page states a free-education mission.
Watch for We could not load the science course pages (the site showed a browser check), so look at the current science course list for your grade before planning around it.
Visit Khan Academy ↗ Facts read on the maker’s page.
Video-based science and math lessons for K-8, each with extras such as worksheets, answer keys and teacher guides. The site says you can watch five lessons free with no account, and teachers can try it free, without a credit card, for a limited time.
The free part: Five free lessons with no account, plus a free trial for teachers; teacher resources need a login.
Paid plans are listed on the pricing page; prices there differ by currency and offer, so check the current figure.
Watch for Teacher resources need a login, and full access after the trial is a paid subscription.
Visit Generation Genius ↗
99. Mystery Science
Mystery Science
A standards-aligned science curriculum for kindergarten through 5th grade, with more than 200 lessons plus engineering and mini lessons. The home page says new users can sign up for a free trial, and the pricing page says free access to all lessons runs until June 30, 2027.
The free part: Free access to all lessons until June 30, 2027 for a teacher who signs up (email or Clever).
Paid memberships follow; the pricing page shows school and homeschool plans, so check the current figure.
Watch for Free access is time-limited and needs an account, and long-term use means a paid membership.
Visit Mystery Science ↗ Facts read on the maker’s page.