Shape and Space - Angles and Lines

Points, Lines, and Line Segments: A point is a tiny position in space represented by a dot. A line is a straight path that goes on forever in both directions, shown visually with arrows on both ends $\leftrightarrow$. A line segment is just a piece of a line with two definite endpoints, looking like a straight bar connecting two dots.

Rays: A ray is a part of a line that has one starting point (endpoint) and continues forever in the other direction. It is drawn as a line with a dot at one end and an arrow at the other $\rightarrow$.

Parallel Lines: These are lines that are always the exact same distance apart and never meet or cross, no matter how long they are drawn. Visually, they look like the two rails of a train track or the opposite sides of a rectangular ruler.

Perpendicular Lines: These are special lines that intersect or meet to form a perfect 'square corner'. This intersection creates what we call a right angle ($90^{\circ}$), appearing like the letter $L$ or the cross in a plus sign $+$.

Angles and Vertices: An angle is the amount of turn between two rays or line segments that meet at a common endpoint called the vertex. Think of the vertex as the 'corner' where the two lines start.

Right Angles: A right angle is a perfect square corner measuring exactly $90^{\circ}$. You can find them in the corners of your notebook, windows, or doors. In diagrams, a small square is often drawn in the corner to show it is exactly $90^{\circ}$.

Acute and Obtuse Angles: These are classified by how wide they open. An acute angle is 'sharp' and opens less than a right angle (less than $90^{\circ}$), like a partially open pair of scissors. An obtuse angle is 'blunt' and opens wider than a right angle but less than a straight line (between $90^{\circ}$ and $180^{\circ}$), like an open hand fan.

Horizontal and Vertical Lines: A horizontal line runs straight across from left to right, like the horizon where the sun sets. A vertical line runs straight up and down, like a flagpole or a standing person.