Build a story you can check
Place the known facts, choose Add or Take Away, identify what is unknown, and make a prediction. Submit your model, then play it forward and undo the change. The story follows the model you submitted, so you can see whether your choices match the words.
Six structures, 48 fixed stories
Practice one-step joining and taking-away stories with an unknown starting amount, change or result. There are 36 guided stories and 12 new-situation stories. Spoken American English and tap controls support the same written story. No dragging or speech recording is required.
A clear view of practice
Parents can use up to four learner profiles with optional nicknames and preset avatars. Learning records distinguish a first independent correct response from completion with help. StoryUndo is for children ages 6–8 who can count to 20 and are beginning addition and subtraction. It is not a complete curriculum or a validated learning assessment.
Six free stories, one full unlock
The first story in each structure stays free: six stories with the complete learning loop. Full Unlock is planned at US$6.99 as a one-time purchase for the remaining 42 stories. No subscription, timed trial or ads. Apple shows the current price in Parents before a purchase. StoryUndo is planned for the US App Store only, on iPhone and iPad with iOS or iPadOS 18 or later.
Local learning, parent choices
Core practice works offline without an app account. Private iCloud learning sync starts off; a parent decides whether to enable it. Purchases, external links, sync and learning backups require a parent check. Full Unlock is configured for Apple Family Sharing; learning records do not automatically move between different family members’ iCloud accounts.