There are huge instances of sexism that most people (we hope) will recognize, like refusing to hire someone because of their gender, or insisting it's a woman's duty to have babies, or refusing to see a woman doctor. These are all real things that still happen in 2018! While many are suitably horrified by such blatant gender discrimination, there's a whole bunch of other instances of sexism we're not as quick to call out.
Illustrator Damian Alexander wrote on Twitter that he overheard a woman tell her son he couldn't have a Wonder Woman doll, telling him it was "for girls." The incident reminded him of a moment in his own life when he wanted to celebrate a hero who happened to be a girl: the character Matilda from Roald Dahl's novel of the same name. Since he's an illustrator, Alexander drew out the whole story as well as his thoughts on how things like this can add up for kids and change how grown men view women.