Atoms and molecules

https://www.coolkidfacts.com/states-of-matter-for-kids/

https://www.ducksters.com/science/the_atom.php

https://www.ducksters.com/science/molecules.php

Quiz 

https://www.coolkidfacts.com/wp-content/uploads/2014/10/Questions-about-States-of-Matter.pdf

https://www.ducksters.com/science/quiz/the_atom_questions.php

https://www.ducksters.com/science/quiz/molecules_questions.php

States of matter

http://www.chem4kids.com/files/matter_states.html

http://www.chem4kids.com/files/matter_states.html

Properties

https://vimeo.com/294085301

Water cycle

https://gpm.nasa.gov/education/videos/earths-water-cycle

Experiments

http://coolscienceexperimentshq.com/convection-how-heat-impacts-liquids/

http://coolscienceexperimentshq.com/make-a-cloud-form-in-a-jar/