Robot-favicon: https://flaticons.net/custom.php?i=6grSPpHGIEIAIZIG9h9YljJuV
Robot-Teacher: https://pixabay.com/vectors/electronics-humanoid-robot-7173509
Blackboard: https://unsplash.com/photos/cGNCepznaV8
Hourglass: https://flaticons.net/custom.php?i=6PWiPpHGIEIAIZIG9h9YljJuV
Infoicon: https://flaticons.net/custom.php?i=jyEUNBUzIJIbIBI8QcXBRlosW
Infinticon: https://flaticons.net/custom.php?i=lQ5cx8I3IZIkIlIV2Tplmb6I8
Bookicon: https://flaticons.net/custom.php?i=6grSPpHGIEIAIZIG9h9YljJuV