Matter and Its Interaction NGSS STEM Lesson & Challenges 5-PS1-4 and 4.5.B cover topics of mixtures, solutions, sorting, floating, settling, sieving, filtration, distillation, and magnetic attraction. Great for teaching if an object sinks or floats, density layers, separation of mixtures, water surface tension and much more. This resource includes: Can you explain the difference between a mixture and a solution?Why do we say that solutions are chemically united? ReadingsExperimentsSeparatin