The Japanese Soroban is effectively a mechanical calculator. Its use trains the mind to visualize and quickly process and understand arithmetic operations--you learn to do math in your head really fast.
The Soroban is a powerful tool that improves the student's understanding of math even--and especially--when put in use from the start. In other words, you give the student a calculator to learn basic addition and it makes them better at doing addition.
Arithmetic is the foundation of Algebra, and Algebra is the foundation of all higher math--Geometry, Calculus, Statistics, Physics, Chemistry, and so on. This minimal investment will improve the teaching of Arithmetic, a first step in improving STEM education.