Developed by Dr Claus Zinn

Computer Scientist and Educational Researcher




Version 1.5
Exercise your Basic Addition / Subtraction Skills
Pyramids is an educational app that primary school kids can use to exercise their basic arithmetric skills.
  • Practising addition (and subtraction)
  • Three levels of difficulty
    • 6 blocks, 10 blocks, 15 blocks pyramids
    • from low to high digit numbers
  • Unlimited number of (randomised) exercises
  • Direct feedback for correct/incorrect sums
  • Intelligent next-step help and error correction
  • Multi-lingual help page (english, german, french, italian)
  • Available for iPad tablets, from iOS7
  • Priced at .99 US cents, 1.09 Euro cents
Compatible with the iPad. Requires iOS7 or later. No WiFi, Edge, or 3G network connection required. No ads.


Lehrer Lämpel: Number Pyramids is an educational app that primary school children can use to practise their basic addition and subtraction skills.

Three pyramids, consisting of 6, 10, and 15 blocks each, need to be filled with numbers. The block layout guarantees that each two blocks have a parent block. The number to be put in the parent block must be the sum of its two lower blocks.

Numbers need to be drag and dropped from the number pile to their correct position.

Incorrect positions are marked red; correct positions are marked green. Whenever there is a new sum constructed, such direct and coloured feedback is given.

Pupils can ask for help at any time. Help first removes an erroneously placed number from its position; if there are no errors, a number from the number pile is moved to its correct position.

The difficulty increases with the larger pyramids.

The app is supported by a small set of basic sound effects. Parents and teachers can thus follow progress by simply listening to the sound.

Lehrer Lämpel: Number Pyramids is available on the iPad, and has been built for iOS8 or later.


Version 1.0

Released on June 22th, 2014
  • Initial Release.

Version 1.1

Released on July 8th, 2014
  • Added support for Italian.
  • Improved error correction and help.
  • Minor bug fix and minor design changes.

Version 1.2

September 28, 2014
  • Added further handle on difficulty wrt. numbers at lower end of pyramid
    • - easy: numbers are less than 10
    • - medium: numbers are less than 20
    • - hard: numbers are less than 30
  • Added option to decided whether pyramid should be pre-filled with some numbers:
    • - no pre-fill of numbers
    • - yes, but all numbers at the bottom
    • - yes, but randomise placement of pre-filled numbers
  • Sound can be switched on/off
  • Minor design changes.

Version 1.3

Submitted November 13, 2014
  • Added new theme: igloos with polar bears
  • Changed font for numbers to Helvetica Neue
  • Minor design changes.
  • Minor bug fixes.

Version 1.4

Submitted October 23, 2015
  • Supports iOS9
  • Minor design changes.

Version 1.5

NEW April 19, 2017
  • Added new theme: blackboard with ghosts
  • design changes.


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