This has most likely been posted here before, but it's incredibly useful.
Interesting show - how calculate the value of the sine, cosine, tangent and cotangent of the angle 0◦, 30◦, 45◦, 60◦, 90◦. The fingers are numbered seq... - Matematyka - Matematyczny Świat wokół nas. - Google+
15 Fun and Educational Activities for Kids
Dry Ice Bubbles - Educational Activities for Kids
Ionic and Molecular Compounds Infographic misses out giant covalent yet lists SiO2 as covalent example.