Above is a fantastic website documenting the Apollo series of missions. You will spend many hours, days, perhaps years, delving into the detailed presentations on these missions. This is truly a masterful compilation of these historic events.
NASA has recently launched new, focused content "For Educators" with STEM activities that occur on the International Space Station. You can follow astronauts demonstrate STEM concepts and use their videos and additional resources to supplement classroom activities.
Mission to Pluto—the first-ever close flyby of the dwarf planet. NASA History was made July 14th when its spacecraft did a flyby of an object after traveling for almost 10 years and more than three billion miles from earth.