Numbers to 20 can be decomposed into 10s and 1s
Below is how the official curriculum organizes it. Each strand will get full lessons like the ones in Grade 1 Mathematics.
Number concepts to 20; ways to make 10
Addition and subtraction to 20 (understanding of operation and process)
Repeating patterns with multiple elements and attributes; change in quantity to 20; meaning of equality and inequality
Direct measurement with non-standard units; comparing and sorting 2D shapes and 3D objects
Concrete graphs using one-to-one correspondence; likelihood of familiar events
Values of coins; monetary exchanges