16.1 - I will only list educational items, not Text Editors etc.
Accessories:
Maps:
Minder: Create, Develop and visualise your ideas:
Education:
Blinken (Simon Says type game - repeat the sequence of the four colours)
GCompris - Great education suite for chlldren aged 2 to 11.
GeoGebra - Create interactive mathematical constructions and applets. (https://www.geogebra.org/)
Kanagram - KDE application - anagram.
KBruch - KDE appllcation - practice fraction exercises.
Kolibri - offline teaching and can be used by schools to share resources. (Kolibri : A Free, Open Source Education for All | Learning Equality)
K Touch - KDE Touchtyping tutor
K Turtle - KDE version of the old Windows Logo education app - program a route for the turtle to get from A to B.
KWordQuiz - KDE flash card and vocabulary training.
Minuet - Music Creation software (https://minuet.kde.org/)
OpenBoard - Interactive Whiteboard software for Schools and Universities.
Step - Simulate Physics Activities. KDE application: (Step - KDE Applications)
Tux Math - fire the laser at the falling sums by entering the correct key combination.
Tux Typing - Typewriting Tutor.
Games: (Educational games)
gbrainy - logic, verbal, calculation and memory tester.
KAtomic - maze game where you have to put atomic elements together in the correct order.
Laby - learn how to program with Ants and spider's webs.
Pentobi - computer version of blokus - get all the different shapes to fit in an oblong.
Potato guy - a compuerised version of Mr Potato - remember them? You got a potato and stuck the eyes, feet and hands, nose into the Potato! (Toy Story anyone?! LOL!)
Quadrapassel - falling blocks game.
Sudoku - Maths game.
Graphics
LibreCAD - Free Computer Aided Design program.
Internet:
Remmina - for remote login to school servers.
Office
Foliate - simple eBook viewer. (Comment: Surprised Calibre is not included, but then again might be too complex for younger end).
Programming
Builder - Build Software for Gnome - (if the Devs approve it that is! LOL!)
Fritzing - Create circuites and PCB's (Printed Circuit Boards).
Science
GNU Octave - 5.2 is present but the latest is 6.x! (GNU Octave)
KAlgebra - Expression Solver and Plotter (KAlgebra - KDE UserBase Wiki)
Kalzium - Brilliant KDE Periodic Table application.
KDE Marble - Not so great equivalent of Google Earth - The Open Street Map element has the wrong post code (=zip code in US) for where I live!
Stellarium - Astronomy application.
Sound and Video
Audacity 2.3.3 - Think this is pre-spyware version.
MuseScore 3 - Great music composition software.
Pitivi - simple video editor.
System Tools
Mozc - Japanese input settings - (Setting up Japanese input method on Linux | Elianiva)
Utilities
Calculator - Basic Mode (default), advanced mode - (Scientific), Financial Mode, Programming Mode (Binary, Octal, Decimal, Hexadecimal), Keyboard Mode - sometimes referred to as 'Paper mode' sic. Linear equations. (Comment - would be even better if it included 3rd Party application, Qalculate, especially for low vision users. (https://qalculate.github.io/)
Dictionary.
Comment - for Tertiary applications, you might want to take a look at Uber Student in live mode. (https://uberstudent.org/)
Lastly, in view of the fact that a lot of the apps are KDE apps, would make sense to ditch Gnome for Plasma (KDE) for future releases. 