Grothendieck "died" in the sense meant by Paul Erdos (stopped doing new mathematical research) at a surprisingly young age, while Israel Gelfand kept going into his nineties, not "dying" (ceasing to be a mathematician) until he "left" (died in the usual sense of the term).

http://www.math.rutgers.edu/~zeilberg/Opinion62.html

Gelfand was a mathematician who also cared deeply about mathematics pedagogy, and his textbooks are delightful.

http://www.amazon.com/Algebra-Israel-M-Gelfand/dp/0817636773

http://www.amazon.com/Functions-Graphs-Dover-Books-Mathemati...

http://www.amazon.com/Method-Coordinates-I-M-Gelfand/dp/0817...

http://www.amazon.com/Trigonometry-I-M-Gelfand/dp/0817639144...

Gelfand poses delightful problems that give students a workout in arithmetic (and CAN'T be done with a calculator) and that build conceptual understanding and interest in higher mathematics.

supplementing the math curriculum we use (Saxon)

For homeschooling, I much prefer Miquon Math

http://www.keypress.com/x6252.xml

for starting out my children, and then the Singapore Primary Mathematics materials (which now have an edition aligned to United States curriculums standards)

http://www.singaporemath.com/Primary_Mathematics_Stds_Ed_s/1...

followed up by the Gelfand textbooks

http://www.amazon.com/Algebra-Israel-M-Gelfand/dp/0817636773

http://www.amazon.com/Method-Coordinates-I-M-Gelfand/dp/0817...

http://www.amazon.com/Functions-Graphs-Dover-Books-Mathemati...

http://www.amazon.com/Trigonometry-I-M-Gelfand/dp/0817639144...

appropriately supplemented by ALEKS

http://www.aleks.com

and EPGY

http://epgy.stanford.edu/district/info.html

I think it would be enlightening if you could provide the textbooks you buy.

Interpreting that as a request to name the textbooks I find useful, I'll do that here.

Elementary mathematics:

Primary Mathematics

http://www.singaporemath.com/Primary_Math_s/21.htm

and

Miquon Math

http://www.keypress.com/x6252.xml

Secondary mathematics:

The Gelfand Correspondence Program series

http://www.amazon.com/Algebra-I-M-Gelfand/dp/0817636773

http://www.amazon.com/Functions-Graphs-Dover-Books-Mathemati...

http://www.amazon.com/Method-Coordinates-I-M-Gelfand/dp/0817...

http://www.amazon.com/Trigonometry-I-M-Gelfand/dp/0817639144...

http://www.amazon.com/Sequences-Combinations-Limits-Library-...

and

Basic Mathematics by Serge Lang

http://www.amazon.com/Basic-Mathematics-Serge-Lang/dp/038796...

and

The Art of Problem Solving expanded series

http://www.artofproblemsolving.com/Books/AoPS_B_Texts_FAQ.ph...

When a student has those materials well in hand, it is time to work on AMC and Olympiad style problem solving,

http://www.artofproblemsolving.com/Books/AoPS_B_CP_AMC.php

http://www.artofproblemsolving.com/Books/AoPS_B_CP_Olympiad....

and also the best calculus textbooks, such as those by Spivak or Apostol.

http://www.amazon.com/Calculus-Michael-Spivak/dp/0914098918/

http://www.amazon.com/Calculus-Vol-One-Variable-Introduction...

http://www.amazon.com/Calculus-Vol-Multi-Variable-Algebra-Ap...

Elementary reading:

By far the best initial reading text is

Let's Read: A Linguistic Approach

http://www.amazon.com/Lets-Linguistic-Approach-Leonard-Bloom...

but there are many other good reading series, including

Primary Phonics

http://www.epsbooks.com/dynamic/catalog/series.asp?seriesonl...

and

Teach Your Child to Read in Ten Minutes a Day

(I devote more time than that to reading instruction, typically, because I use multiple materials)

http://www.amazon.com/Teach-Your-Child-Read-Minutes/dp/14120...

and quite a few others. There is more junk than good stuff among elementary reading materials, alas.