UPDATE: There is no actual graph or tree which I have found, but for anyone looking there are some usable assets which are discussed here: Is there a tag/competence classification for mathematics education?
ORIGINAL: I would like to find a good skills tree for mathematics, so that I can learn the prerequisite knowledge and skills for any given set of skills. For example, if one wants to learn algebra, one should have fluency with basic math operations like addition and multiplication, a solid understanding of fractions, percents, and decimals, ratios and proportions, et al.
Is there such a published skills tree for mathematics? I have been unable to find one online with a reasonable search effort.