A cute zoo theme sets the tone for a problem-solving activity which primes early learners for division. They separate zoo animals into equal groups and then write an equation that expresses the action. 

In 1879, Sir William Crookes discovered the fourth state of matter, plasma. The presentation covers states of matter, phase changes, density, pressure Pascal's Principle, buoyant force, Archimedes' Principle, Bernoulli's Principle,...