In mathematics, two-dimensional shapes are flat, and they have only length and width. Two-dimensional shapes are often called 2D shapes. Some common examples of 2D shapes include squares, rectangles, circles, triangles, and polygons.

1. **Number of Sides:** Two-dimensional shapes can have different numbers of sides. For example, a triangle has 3 sides, a square has 4 sides, and a pentagon has 5 sides.

2. **Vertices:** The point where two sides of a shape meet is called a vertex (plural: vertices).

3. **Angles:** Two-dimensional shapes can have different types of angles, such as right angles, acute angles, and obtuse angles.

4. **Diagonals:** Some 2D shapes have diagonals - lines that connect non-adjacent vertices.

When studying two-dimensional shapes, it's important to understand the properties and characteristics of different shapes. Here are some key points to focus on:

- Identify and memorize the names and properties of common 2D shapes (square, rectangle, circle, triangle, etc.).
- Learn how to calculate the perimeter and area of different 2D shapes.
- Understand the concept of angles and how they are related to two-dimensional shapes.
- Practice drawing and identifying different 2D shapes to reinforce your understanding.

By mastering the properties and characteristics of two-dimensional shapes, you'll be well-prepared to solve problems and work with geometric concepts in mathematics.

Study GuideAlgebraic Equations Worksheet/Answer key

Algebraic Equations Worksheet/Answer key

Algebraic Equations Worksheet/Answer key

Algebraic Equations Worksheet/Answer keyAlgebraic Equations Worksheet/Answer key

Algebraic Equations Worksheet/Answer keyAlgebraic Equations

Algebra (NCTM)

Represent and analyze mathematical situations and structures using algebraic symbols.

Recognize and generate equivalent forms for simple algebraic expressions and solve linear equations

Grade 6 Curriculum Focal Points (NCTM)

Algebra: Writing, interpreting, and using mathematical expressions and equations

Students write mathematical expressions and equations that correspond to given situations, they evaluate expressions, and they use expressions and formulas to solve problems. They understand that variables represent numbers whose exact values are not yet specified, and they use variables appropriately. Students understand that expressions in different forms can be equivalent, and they can rewrite an expression to represent a quantity in a different way (e.g., to make it more compact or to feature different information). Students know that the solutions of an equation are the values of the variables that make the equation true. They solve simple one-step equations by using number sense, properties of operations, and the idea of maintaining equality on both sides of an equation. They construct and analyze tables (e.g., to show quantities that are in equivalent ratios), and they use equations to describe simple relationships (such as 3x = y) shown in a table.