Mathe-Trainer

Mental arithmetic practice on a tablet, for children from their first school
year. The app measures the time to the correct answer and turns it into a
learning curve and leaderboards, where several children on the same device
compete with each other.

The interface is in German only.

It runs entirely offline. No account, no ads, no analytics and no internet
permission - the app cannot send anything anywhere.

76 lessons in nine groups

Counting and comparing pictures for the youngest, then addition and
subtraction up to 10, 20, 100 and 1000 - with and without carrying - the
times tables forwards and backwards, division with and without a remainder,
order of operations, telling the time and handling money.

Stars for care, lightning bolts for speed

Two separate axes on purpose. Stars follow the error rate, bolts the time per
task. A child who works carefully earns the stars even slowly.

What parents can set

Behind a PIN: which groups a child is offered at all, how long they may
practise in one stretch and per day, how many runs of one lesson still count
towards records in a day, and whether difficult tasks are woven back in.

Assignments too: give a child a lesson, daily or weekly, or as a plan for one
named day, with a minimum of stars and bolts to reach.

Your data stays with you

Everything lives in a database on the device. A backup is written only when
you ask for one, and handed to Android's share sheet - where it goes is your
choice.