What is a number line?
A number line turns addition and subtraction into something you can see and count. Adding means hopping forward; subtracting means hopping back. Here a friendly frog jumps one step at a time from a starting number, so a child watches each hop and lands right on the answer. It covers the numbers 0 to 20, the range where early addition and subtraction are learned.
Counting on and counting back
The tool models two key early strategies: "counting on" for addition and "counting back" for subtraction. Each jump is drawn as a numbered arc above the line, and the equation fills in as the frog moves, connecting the picture to the symbols. A speed control lets slower counters keep up, and Watch again or Skip put the pace in the child's hands.
For home and the classroom
Numbers stay between 0 and 20, with gentle guardrails so a sum can't run past 20 or a subtraction below 0 — mistakes become a friendly hint, not a wrong buzzer. It takes input from the steppers or the keyboard, respects reduced-motion, and collects nothing, so it's ready to hand straight to a child.
For parents and teachers: a visual aid for counting on and back, best paired with guided practice.
Frequently asked questions
What ages is it for?
It suits children around ages 5 to 8 (kindergarten to second grade) building addition and subtraction within 20.
How does a number line help?
It makes the count visible: adding hops forward, subtracting hops back. Seeing the jumps builds the sense behind the numbers before written methods.
What is a number line?
A straight line with numbers marked at equal spaces. It shows order and distance, so bigger numbers are to the right and smaller ones to the left.
How does a number line help with addition and subtraction?
To add, you jump right; to subtract, you jump left. Counting the jumps makes the operation easy to picture.
Can a number line show negative numbers?
Yes — numbers to the left of zero are negative. The line makes it clear that −3 is less than −1, and that both are less than zero.