Developed by Dr Claus Zinn

Computer Scientist and Educational Researcher

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Lehrer Lämpel

Version 1.2
Lehrer Lämpel: Addition

An educational app that supports primary school kids to train their addition skills.
  • Practising multi-column addition
  • Various levels of difficulty
    • from 2 to 5 digit numbers
    • with and without borrowing
  • Worksheet with 3-digit number addition tasks
  • Unlimited number of (randomised) exercises
  • Support for self-defined addition tasks
  • Direct feedback for correct/incorrect steps
  • Intelligent next-step help and error correction
  • Multi-lingual help page (english, german, french)
  • Available for iPad tablets, from iOS7
  • Price at .99 USD, .99 Euro
Compatible with the iPad. Requires iOS7 or later. No WiFi, Edge, or 3G network connection required. No ads.


Lehrer Lämpel is an educational app that supports primary school children (usally 3rd grade) to practise their multi-column addition skills.

Easy drag & drop of numbers to the blackboard.

Immediate feedback option where incorrect steps are immediately marked red and where correct steps are immediately marked green.

Pupils can ask Lehrer Lämpel for help at any time. Help first removes an erroneously learner step; if there are no errors, a single step is performed towards the solution.

All teacher steps towards the solution are followed-up with a step explanation as well.

Various degrees of difficulty guided by the number of digits the two numbers can have, and whether borrowing operations are required.

Supports self-defined addition tasks and there is a work-sheet, and randomised exercises

Supports English, French and German.

Available on the iPad, for iOS7 or later.


Version 1.0

Released on September 28th, 2014
  • Initial Release.

Version 1.1

Released on November 6th, 2015
  • NEWAdded support for iOS9.
  • Improved design
  • Voice Synthesis to read aloud help!

Version 1.2

Released on Feburary 24th, 2017
  • The swish and fanfare sound are no longer played as system sounds, that is, they can now be switched off or their volume turned down.
  • Minor App Icon Redesign
  • Improved Help Menu


Privacy Policy

Our privacy policy is rather simple. We do not collect any information from you and your child when using our app or browsing our website.

You or your child will never be prompted to provide any sort of information in our app. You are free to use the contact form on the website to give us your feedback, ask questions, elicit new app features, or file a bug report. For this, you can equally contact us at

We will use your contact information only for being able to reply to your requests. It will not be shared with anybody else.

Our app is solely financed by its price tag, there are no in-app purchases, and the app is ads-free.


Contact Us

Please use the following form for questions, feedback, feature requests etc.

Our email:

Postal Address

Dr. Claus Zinn, Diplom-Informatiker (Univ.)
In der Gebhardsoesch 33
78467 Konstanz, Germany