Is the 150 year old RAY's ARITHMETIC series more rigorous than todays Common Core Math?
The value of Intellectual Arithmetic is so highly appreciated by instructors that little need be said in its commendation When properly taught it is one of the most useful and interesting studies in which pupils can engage and should be omitted by no one By its study learners are taught to reason to analyze to think for themselves while it imparts confidence in their own reasoning powers and strengthens the mental faculties.
Below are the links to Ray's Arithmetic books, and the answer keys.
Ray's New Primary Arithmetic (K-2nd Grade)
Ray's New Intellectual Arithmetic (3-4th Grade)
Ray's New Intellectual Arithmetic (Answer Key for 3-4th Grade)
Ray's New Practical Arithmetic (5-6th Grade)
Ray's New Practical Arithmetic (Answer Key for 5-6th Grade)
Books in the Ray's Math Series
Key to Ray's New Arithmetics: Intellectual and Practical
Ray's New Primary Arithmetic for Young Learners
Ray's New Intellectual Arithmetic
Ray's New Practical Arithmetic
Ray's New Higher Arithmetic
Ray's New Test Examples
Ray's New Elementary Algebra
Ray's New Higher Algebra
Ray's Test Problems in Algebra
Ray's Plane and Solid Geometry
Ray's Geometry and Trigonometry
Ray's Analytic Geometry
Ray's Elements of Astronomy
Ray's Surveying and Navigation
Ray's Differential and Integral Calculus