### 5th Grade, Activity 343: Classify Two-Dimensional Figures into Categories Based on their Properties

Understand that attributes belonging to a category of two-dimensional figures also belong to all subcategories of that category.

For example, all rectangles have four right angles and squares are rectangles, so all squares have four right angles.

### 5th Grade, Activity 280: Convert Like Measurement Units Within a Given Measurement System

Convert among different-sized standard measurement units within a given measurement system, and use these conversions in solving multi-step, real-world problems (e.g., convert 5 cm to 0.05 m; 9 ft to 108 in).

### 5th Grade, Activity 217: Apply and Extend Previous Understandings of Multiplication and Division to Multiply and Divide Fractions

Interpret a fraction as division of the numerator by the denominator (a/b = a ÷ b). Solve word problems involving division of whole numbers leading to answers in the form of fractions or mixed numbers, e.g., by using visual fraction models or equations to represent the problem.

### 5th Grade, Activity 171: Use Equivalent Fractions as a Strategy to Add and Subtract Fractions

Add and subtract fractions with unlike denominators (including mixed numbers) by replacing given fractions with equivalent fractions in such a way as to produce an equivalent sum or difference of fractions with like denominators.

For example, 2/3 + 5/4 = 8/12 + 15/12 = 23/12. (In general, a/b + c/d = (ad + bc)/bd.)

### 5th Grade, Activity 70: Understand the Place Value System

Use place value understanding to round decimals to any place.

### 5th Grade, Activity 16: Write and Interpret Numerical Expressions

Write simple expressions that record calculations with whole numbers, fractions, and decimals, and interpret numerical expressions without evaluating them.

For example, express the calculation “add and 7, then multiply by 2” as 2 × (8 + 7). Recognize that 3 x (18,932 + 9.21) is three times as large as 18,932 + 9.21, without having to calculate the indicated sum or product.

### 4th Grade, Activity 419: Geometric Measurement: Understand Concepts of Angle and Measure Angles

Recognize angles as geometric shapes that are formed wherever two rays share a common endpoint, and understand concepts of angle measurement:

c. An angle that turns through n one-degree angles is said to have an angle measure of n degrees.

### 4th Grade, Activity 386: Solve Problems Involving Measurement and Conversion of Measurements from a Larger Unit to a Smaller Unit (Measure Problems Solving)

Apply the area and perimeter formulas for rectangles in real-world and mathematical problems. For example, find the width of a rectangular room given the area of the flooring and the length, by viewing the area formula as a multiplication equation with an unknown factor.

### 4th Grade, Activity 237: Build Fractions from Unit Fractions by Applying and Extending Previous Understandings of Operations on Whole Numbers

Understand a fraction a/b with a > 1 as a sum of fractions 1/b. (Denominators are limited to 2, 3, 4, 5, 6, 8, 10, 12, and 100.)

a. Understand addition and subtraction of fractions as joining and separating parts referring to the same whole. Example: 3/4 = 1/4 + 1/4 + 1/4