For my 4th and 5th graders

For my 3rd graders You can stop at 4:00 mark.

The image above is the most child friendly image I could find that explains how stars go the routes they go.  Notice line 1: A protostar tries to start up.... but it can't. A protostar must have at a bare minimum the mass of 13 JUPITERS or it can not "flame on". If it has less, it can not become a traditional star. Instead it fizzles into a brown dwarf which is neither a real star nor a real planet.  It will stay like this its entire lifetime.  Line 2: If its mass is barely over 13 Jupiters it will become a cute little red dwarf.  When a red dwarf fizzles out though it only turns into a white dwarf and then a black dwarf eventually.  White Dwarf is the eventual end of smaller mass objects... once you hit the "blue range" or higher mass objects thats when things turn into either neutron stars/pulsars/or black holes.    The BIGGER a star is the more mass it is, the BRIGHTER it shines in the night sky... but the COOLER the temperature is.  The SMALLER a star is, the less mass, shines not as bright in the night sky but the HOTTER the temperature is.

These are picture of MAIN Sequence stars only. No Brown or White Dwarfs. No Super Giants.    Notice the smaller it is the HOTTER it is. Red is hot....  Notice the bigger it is the COOLER it is. Dark Blue is cold....   The luminosity is the "flashlight side".  So the BIGGER it is... the more it shines in the night sky and can be seen by normal human eyes.  The smaller it is.... the less bright it shines and can only be seen by binoculars or normal telescopes. Sometimes not even those. Sometimes only with radio telescopes or spectral telescopes.  The "M" beside each dot is weight. The smaller you are.... the less you weigh. The bigger you are the more you weigh. Which means you have more "guts" to help you shine bright. But that also means you have more "skin" to heat up making it harder to be warm. This is why SUPER BIG STARS shine big and bright... but have cold skin.