Subtraction

What is subtraction?

Subtraction answers “how many are left?” when you take some away from a group. Writing it as a − b means start with a, remove b, and see what remains. Seeing that story play out — objects actually leaving, then counting the rest — is what makes the idea stick for young learners.

How to use this tool

• Take away — begin with a group of counters, press play, and watch each one drift off one at a time. The counters that remain light up and get counted: 1, 2, 3…
• Number line — hop backward from the starting number to the answer, landing on every number along the way.
• Use the steppers to set the starting amount and how many to take away, and the range to work within 10, 20, or 100.
• Play the whole thing, take it one step at a time, adjust the speed, or mute the voice.

Why it helps

Children meet subtraction through two big mental models: take away (removing objects) and counting back (stepping down a number line). Showing the same fact both ways builds flexible number sense and helps the written equation feel like a picture they already understand. Hearing each number named aloud connects the symbol, the word, and the amount.

Good for

Kindergarten through 3rd grade — from first “take away” stories within 10, to counting back within 20, to subtracting larger numbers up to 100.