GRADE 1
 Add and subtract whole numbers to 20
 Add and subtract money amounts to 20¢, using coin manipulatives and drawings
 Recognize the inverse relationship between addition and subtraction (e.g., since 4 + 5 = 9, then 9 – 5 = 4) and apply this understanding in doing calculations
– Focusing on the Fundamentals of Math – A Teacher’s Guide, p.5
Text Resources
This curated list of documents have been selected to help you gain a deeper understanding of the above selection from “Focusing on the Fundamentals of Math – A Teachers Guide”. Each link will take you directly to the relevant section within the document.
A Guide to Effective Instruction in Mathematics K6, Vol 5, Teaching Basic Facts and Multidigit Computations 

The Mathematical Territory Between Direct Modelling and Proficiency, What Works 