This blog is written for first-grade students who are now dependent on online education, which is under lockdown due to the COVID-19 pandemic. To ensure a seamless transition when regular classes start, an attempt has been made to conform this blog to the COMMON CORE STATE STANDARD INITIATIVE. The methodology is explained using solved examples. The assignments can be printed out and solved offline. The Section numbers follow the numbers of the core standard document mentioned above.
Section OA.A.1:
1. Subtraction :
Solved example: There are fourteen girls in the field. Five of them are carrying a ball each. How many girls are there without a ball?

We can directly count. We will do that later to check our answer! Let us now learn the subtraction rule:
The “whole” set of fourteen girls consists of two parts: Part 1 features girls with a ball, and Part 2 features girls without a ball.

Let us separate the girls in Part 1.

The remaining girls without balls belong to Part 2

Out of the whole set of fourteen girls, we have to “separate” or “remove” Part 1 to get Part 2
whole – Part 1 = Part 2
Let us check out our answer. Count the girls in Picture 3. The number of girls without a ball is 9!
Now, we are ready to attempt the exercises.