### 2nd Grade, Activity 184: Use Place Value Understanding and Properties of Operations to Add and Subtract

Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.

### 2nd Grade, Activity 163: Understand Place Value

Read and write numbers to 1000 using base-ten numerals, number names, and expanded form.

### 2nd Grade, Activity 138: Understand Place Value

Read and write numbers to 1000 using base-ten numerals, number names, and expanded form.

### 2nd Grade, Activity 13: Represent and Solve Problems Involving Addition and Subtractionâ€‹

Use addition and subtraction within 100 to solve one-and two-step word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.

### 1st Grade, Activity 426: Reason with Shapes and their Attributes

Partition circles and rectangles into two and four equal shares, describe the shares using the words halves, fourths, and quarters, and use the phrases half of, fourth of, and quarter of.

Describe the whole as two of, or four of the shares. Understand for these examples that decomposing into more equal shares creates smaller shares.

### 1st Grade, Activity: 272: Use Place Value Understanding and Properties of Operations to Add and Subtract

Given a two-digit number, mentally find 10 more or 10 less than the number, without having to
count; explain the reasoning used.

### 1st Grade, Activity 247: Understand Place Value

Compare two two-digit numbers based on meanings of the tens and ones digits, recording the results
of comparisons with the symbols >, =, and <.