See https://news.ycombinator.com/item?id=13713199
Also I've been posting a lot on math lately so if you want more examples and references, scroll through my HN posts and comments (I tend to cite everything so there's a ton of links in there).
Of special note, as others have started to discover, Grant Sanderson's 3Blue1Brown YouTube channel is a masterwork, an evolutionary tour de force in the way mathematical concepts and visualized and presented.
Grant wrote a custom software library (in Python, on Github) that enables him to create video visualizations to show the geometrical intuition behind abstract mathematical concepts. And this is key. Being able to visualize the geometric structure and transformations the mathematics is describing is the key that's been missing from the way math is traditionally taught, and this lack of visual intuition is why many find math so hard to penetrate.
3Blue1Brown's YouTube channel : https://www.youtube.com/channel/UCYO_jab_esuFRV4b17AJtAw
Go there first to develop your visual intuition -- watch all his videos, and then watch them again, and again -- and soon you'll discover your new, powerful mental models forming, and things that were once opaque will suddenly become clear.
Start with his "Essense of Linear Algebra" series (it's one people are usually blown away by, and it's being discussed on HN a bunch lately).
He's going to release an "Elements of Calculus" series in April, and while Calculus is usually a prerequisite to Linear Algebra, it's not critical for understanding the visualizations the way it's presented here. But if you need a refresher, MIT's "Big Picture Calculus" is great (it's linked to in the HN thread I referenced in the first paragraph).