Visualizing 1 + 2 on the Number Line

We want to understand the basic arithmetic operation:

$1 + 2 = ?$

Step 1: Interpret the numbers

• The number 1 is our starting point on the number line.
• The number 2 is how many steps to the right we move from 1.

Step 2: Use the number line model

A number line is a straight horizontal line where:

• Each point corresponds to a real number.
• Moving right means adding (increasing the value).
• Moving left means subtracting (decreasing the value).

To compute $1 + 2$:

1. Start at $x = 1$ on the number line.
2. Move 2 units to the right:
   • After moving 1 unit, you are at 2.
   • After moving the 2nd unit, you are at 3.

Step 3: Result

So the endpoint of this move is:

$1 + 2 = 3$

What the visualization shows

This interactive visualization lets you:

• Slide the first addend (starting position) along the number line.
• Slide the second addend (how far you move to the right).

The canvas will display:

• A horizontal number line centered on the screen.
• A starting marker at the first number.
• A jump arrow showing how far you move to the right.
• A result marker at the sum.

The neon colors highlight:

• Cyan: the number line and tick marks.
• Pink: the starting point and labels.
• Yellow: the jump arrow and the result point.

Mathematically, for any integers (or real numbers) $a$ and $b$ you select with the sliders, the visualization illustrates:

$a + b = \text{sum}$

and shows it as a translation (shift) along the number line.