Add & Subtract within 20

Addition within 10

Red apples on the left, green apples on the right. Combine the two parts, count in your head, then tap the number keypad to choose the total. Correct answers make the equation glow; wrong ones turn red so you can retry.

additioncombinewithin 108min

FreeEasy

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Subtraction within 10

Some dots in the row are crossed out: those are the ones taken away. Look at the picture, work out how many are left, and tap the number keypad. Correct answers make the equation glow.

subtractiontake awaywithin 108min

FreeMedium

🔟

Make Ten (9 plus)

Nine red dots don't quite fill the ten-frame, with some blue dots beside them. Tap “Move 1 over” and watch a blue dot complete the frame — suddenly 9 + something becomes 10 + the rest, easy to see at a glance.

make tencarrying9 plus10min

FreeMedium

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Break Ten (teen minus 9)

The ten-frame holds 10 dots with a few more beside it. Tap “Take away 9” and watch nine dots in the frame get crossed out one by one, leaving exactly 1 — so teen − 9 becomes 10 − 9 = 1, plus the loose ones.

break tenborrowingteen minus 910min

Related Themes for This Grade

Numbers within 20

Get to know numbers up to 20: count objects one by one, compare which group has more, and see that teen numbers are made of one ten and some ones.

Meet the Shapes

Get to know common flat shapes (circle, triangle, square, rectangle) and solid shapes (box, cube, cylinder, sphere) through quick tap-to-find mini games.

Tens, Ones & Comparing

Build two-digit numbers with ten-rods and one-squares: compare the tens first and only check the ones when they tie, then press +10 / −10 to see that only the tens digit changes.

Telling Time: Hour & Half Hour

Meet the hour hand and the minute hand, then learn to read o'clock and half past times: the minute hand points at 12 for o'clock and at 6 for half past.