One move a year
six books.
One argument.
The years are not the same year with bigger numbers. Grade 1 asks a child to hold a rule in their head while they use it. Grade 2 shows them that mathematics has parts that are not arithmetic. Each year after that adds a different kind of move and reuses the same objects, shapes, graphs, maps, coins and codes, as material for it. That order is also the order in which the moves are hard: a first grader can follow a rule, a third grader can be systematic, a sixth grader can hold a variable.
Why this, why now
Elementary math is about quantity.
This is about structure.
Discrete mathematics asks how things connect, how many arrangements exist, and whether something is possible at all. Because it leans on reasoning rather than computation, it reaches students that arithmetic practice leaves behind, and it stretches the ones who finish early.
It gives them proof
A whole year of the line, Grade 4, is about things that cannot be done: two colors will not work, five dots cannot each have three lines, the bridge walk is impossible. Explaining why is a kind of thinking the regular curriculum rarely asks for at this age.
It feeds the pacing guide
Loops are repeated addition. Grids are arrays. Binary is place value. Factor rectangles are 4.OA.4 in disguise, and some students arrive at arrays through the loop who never got there through the array.
It needs almost nothing
Crayons, counters and a photocopier. No devices, no kits, no subscription, no training week before you can start.
It is checked, not asserted
Every one of the 2,231 numeric answers in the 6 newest teacher guides is recomputed from the problem as the workbook states it, by a script that ships with the source and runs on every build. If a fix to a page changes an answer, the build fails until the guide agrees.
Questions
What teachers ask.
Anything not answered here is worth an email. We would rather field the question than have a school guess.
Pilot a classroom
One teacher.
One year.
No cost.
We are placing these years in elementary classrooms across the San Gabriel Valley. A pilot is one teacher, one class, one school year, materials and support provided. No year has been run start to finish yet, and the first teacher to do it will change how every later book gets written.