Solve. Spell. Reward. 💰
Ever heard of drachmas? 🪙
Well drachmath is not the old Greek currency with a... lisp, but a game that trains your kids in
maths and spelling while they earn pocket money.
The concept is simple: Kids solve math and spelling problems and earn "coins" for each correct answer.
The kid shows their score and the coins can be exchanged for money or other rewards by their parents.
Once the "transaction" is complete, the device is reset and the game can start over again.
The problems are generated randomly and can be customized to suit the child's learning level.
Currently, addition, subtraction, multiplication and division problems are supported,
as well as spelling in Greek and English.
drachmath runs on Seeed Studio's Wio Terminal.
It is a small, portable device with a TFT screen and buttons that can be programmed to run whatever you want.
drachmath works on other Arduino-compatible devices as well,
but you would first need to make slight modifications to the code.
The inspiration for drachmath came from my own experience as a child.
My father created a similar game for me in QBasic in the 1990s.
For each correct answer I would earn, literally, a drachma.
While my motive back then was rather selfish, it gamified my learning and motivated me enough to practice in maths and spelling.
30 years later, I thought of creating a similar game but adjusted to the modern times
and how children interact with technology.
Specifically, I did not want to increase screen time for kids.
This is why drachmath is not an app you can play on your phone or computer.
Instead, it works on small, single-purpose devices (like Wio Terminal) that can "not" be used for anything else.
At least not until they learn how to program the Wio Terminal themselves, which is not a bad idea at all. 😂
drachmath is an Arduino (C++) sketch that is designed to run on Wio Terminal.
With some modifications, it could run on other Arduino-compatible devices as well since there are not any
dependencies on custom-made hardware or the Wio Terminal's microcontroller.
drachmath.ino contains the game's transition flows, while the quiz-related code is found in header file(s).
Almost everything not in the drachmath.ino file is a class or function template.
As a result, code might be somewhat difficult to read and feel over-engineered.
To be honest, both of your assessments are correct.
I wanted to experiment with making things "generic" and "reusable", even though I knew it is very unlikely
the same code will be used in another project or platform.
Additionally, I avoided using the C++ STL despite Wio Terminal supporting quite a lot of it.
The purpose was to make the code easy to port to other Arduino-compatible devices, with more limited resources,
that might not have STL support. Again, this is all theoretical and done for the sake of experimentation and
practice, something crucial in the age of LLMs.
Overall, the user interface starts with a main menu which allows the user to enter the maths or the currently selected spelling quiz. There is a settings menu, enabling the user to change the difficulty of the problems among other things. The user can also view their stats, i.e. their current score and the number of correct and incorrect attempts for each quiz. Settings are saved persistently if a MicroSD card is present. The MicroSD card is also required for the spelling quizzes since the word lists and the Greek font are stored there.
Wio Terminal has 3 buttons and a 5-way joystick that are used for navigation.
The buttons allow the user to select the current menu item, go back to the previous menu, confirm
a solution to a spelling or math problem, as well as delete the letters or numbers they have typed.
There is a battery indicator on the top right corner of the screen, under the score label,
visible when the device is powered up by the Wio Terminal Chassis Battery.
The battery is not required for drachmath to work, but if you want to make the device truly portable,
I highly recommend it.
The most "intricate" part of the code are the spelling quizzes where two different approaches are used due
to differences between English and Greek.
In both quizzes, the user is presented a word with some missing letters without it being obvious how many
letters are missing since this could "spoil" the right answer.
In Greek, it is straight-forward to generate a list of homophones, i.e. letters or combinations of letters (diphthongs)
that sound the same. So whenever there is an "i" sound in a word, there's a very specific set of plausible ways
to spell it. The user is presented with the said set of alternatives and they have to select the correct one.
On the other hand, in English it is more difficult to generate a list of plausible homophones as solution candidates.
I could not find a way that does not require preprocessing the word list and can determine plausible alternatives
on the fly. Additionally, English words that sound almost the same, may have multiple correct spellings, e.g. meat and meet. Consequently, presenting just the word with some alternatives was not enough.
Instead, for English, the following choice was made: Present the user with the entire alphabet and the problem/word within a sentence. The right word choice can sometimes still be ambiguous, but it happens less often.
To summarize, the Greek spelling quiz is more "multiple-choice" oriented. The user is presented with a word that is
missing one or two letters. Then, there's a keyboard with plausible alternatives for the missing letters.
The English spelling quiz presents a user with a sentence and a word with missing letters. The user
has to select the missing letters from a keyboard with the entire alphabet.
The approach is a bit assymetrical but a good enough compromise to make both quizzes work without requiring intense
preprocessing of the word lists.
Lock the current settings by placing a file named lock_settings.txt in the root directory of the MicroSD card.
If the first line of the file is 1, the user will be able to view the settings but not change them.
This way you can be "sure" your kids are solving problems at the intended difficulty level.
- Arduino IDE to flash the code
drachmathcode (this repository)- Seeed Studio's TFT_eSPI library
- Seeed Studio's Filesystem library
- Seeed Studio's SFUD library
- SparkFun's Fuel Gauge library
- sd directory contents copied to the root of a FAT32-formatted MicroSD card
- Greek word list
- LLM generated
- English word list
- Anki database dump and LLM generated
- Greek font
- Ubuntu font, size 32, converted to .vlw format (instructions)
- Greek word list
- Wio Terminal (affiliate link)
- Wio Terminal Battery (affiliate link)
- MicroSD card (for persistent settings, Greek font and word lists)