10 ms·

Numworks: open-source, Python-compatible handheld graphing calculator

158 points by 0xb100db1ade 8y ago

florence123 8y ago
"It is also permitted for use on the SAT by the College Board starting with the August 2018 administration." That's ridiculous. Privatized standard testing seems like a bad deal for folks who can't afford these expensive calculators.
- madengr 8y ago
  I’d hope a calculator is useless for the tests, as they are for most math courses. I’m sure eBay is riddled with these stupid TI type graphing calculators, so anybody can afford one.
- marmaduke 8y ago
  The point is that schools will only buy bunches of these things for teaching if they’re approved for use on the exams.
  - changingmylife 8y ago
    the same schools that can't afford pencils and paper for the students so teachers have to buy supplies out of their own pockets?
  - florence123 8y ago
    The point is that it seems flawed that these are approved for exams, not that this isn't a good business decision on the part of the company advertised here.
kfogel 8y ago
It's not open source; the Hacker News headline is wrong. The Numworks web site does not claim it's open source, by the way -- the problem is only in the headline here. The license is Creative Commons Attribution-NonCommercial ShareAlike (CC-BY-NC-SA), and the presence of the "NonCommercial" clause makes it unambiguously non-open-source. If that clause were not present, CC-BY-SA would still be an odd license to use for software anyway, but because of the NC clause we never get to that issue.
- marmaduke 8y ago
  Source appear to be on GitHub. Non commercial is not incompatible with open source. It makes sense to me that to get the investment required to fund this, you’d want sole rights to commercialize. Nothing prevents someone else from building a cheaper DIY version as long as they don’t sell it. For example it could be a local college class exercise to build these from scratch for local high school. That’s not imaginable for the TI calculators (which these seem to aim to replace)
  - kfogel 8y ago
    Source being on GitHub does not equal "is open source". Restrictions on commercial use are incompatible with open source. The Open Source Initiative, which coined the term and evaluates licenses for compatibility with the Open Source Definition (see https://opensource.org/definition https://opensource.org/definition), is crystal clear on this point: if your license has a field-of-use restriction -- such as a restriction on commercial use -- then it's not open source. This is why Numworks is careful not to describe their software as "open source", to their credit.
    - PurpleRamen 8y ago
      It may not be "Free Source", but if the source is open in the sense if being accessable, then for normal people it is open source. One organization using words in a specific way, doesn't negate all other legit interpretations of those words. It's an unsolvable problem they created there.
      - cpks 8y ago
        Nope. Open Source is a trademark precisely to avoid this sort of misuse. It's not a "what it means to whomever" sort of deal. That was done in part due to intentional (and damaging, if ultimately unsuccessful) efforts to undermine the meaning of terms like 'Free Software' by Microsoft back when the FSF was a fledgling movement and Microsoft was an evil empire. I don't mean to imply negative things about the company. The license is still a heck of a lot better than fully proprietary -- I love the product in part for that reason -- but it's definitely not 'open source' or 'free software' as the headline implies. (I don't think the company claims it is either)
dbcurtis 8y ago
It should be pointed out that this is Micropython, not the Python that you are probably used to. Micropython is great stuff, I’m a huge fan, but it is different from CPython in noticeable ways. They seem to have simply copied a source snapshot over; I’m not sure what that means for incorporating updates and fixes to the Python system. Maybe they needed a fork for some reason. I do wish their documentation gave a little more credit to the Micropython project.
- tyingq 8y ago
  The device does appear to be capable of receiving updates: https://workshop.numworks.com https://workshop.numworks.com Concur on the credit thing though.
  - dbcurtis 8y ago
    Yes, you can update the device. My comment was more about how Numworks can practically integrate Micropython updates. It seems like maybe it could be a Git submodule so that changes were easier to merge. Tracking Micropython bug fixes and enhancements is going to be very labor intensive unless I am missing something here. (Admittedly, I didn’t spend a lot of time nosing around Numwork’s source repo. I have spent a lot of time nosing around the Micropython repo to do my own tweaked builds.)
pietroglyph 8y ago
It's always amazed me how, in 2018, TI calculators with software and hardware from 10 years ago still cost $100+ dollars [0] and command a near monopoly in US secondary schools (which, I suppose, is why they still cost that much). For that price you can get a significantly more powerful and functional mobile phone [1] (see 24K of ram vs. 2GB, 96x64 screen vs. 720 x 1280)! The space needs competition, and I hope Numworks gives TI a run for their money (the calculator is even allowed on the big standard exams), but schools are so standardized on TI calculators (and generally slow-moving) that change will be hard. Casio has also tried to break into this space with significantly cheaper calculators (which are also allowed on standardized exams), but they have failed to gain significant traction so far. A relevant XKCD (of course): https://xkcd.com/768/ https://xkcd.com/768/ A related piece of journalism: https://wapo.st/1Cl0Vyf https://wapo.st/1Cl0Vyf [0]: https://www.amazon.com/dp/B0001EMM0G/ https://www.amazon.com/dp/B0001EMM0G/ [1]: https://www.amazon.com/dp/B01H2E0KVA/ https://www.amazon.com/dp/B01H2E0KVA/
- fafner 8y ago
  More like hardware from 20 years. Yeah I hope the TI monopoly gets broken. Numworks looks exactly like the calculator I was dreaming about when I was in uni.
  - craftyguy 8y ago
    Actually, more like hardware from 40 years ago. The Z80 processor was released in like the mid 70s.
- qubex 8y ago
  I’ve been using both a Texas Instruments Nspire and an HP Prime, and I definitely find the latter to be preferable as it’s leaps and bounds beyond the former in terms of symbolic algebra.
- escherplex 8y ago
  Agree with you there. You may have habituated to TI-89s back at school (still have two) but by today's standards, graphics are super low-res and UI reminds you of trying to manipulate a rubik's cube. And yet it's still a goto on Amazon for about US$140.
Ecco 8y ago
You may want to check out: The whole calculator running in a browser, thanks to emscripten : https://www.numworks.com/simulator/ https://www.numworks.com/simulator/ An interactive PCB viewer, in the browser again : https://www.numworks.com/resources/engineering/hardware/electrical/pcb/ https://www.numworks.com/resources/engineering/hardware/elec... Full schematics https://www.numworks.com/resources/engineering/hardware/electrical/schematics/ https://www.numworks.com/resources/engineering/hardware/elec... And of course the whole source code to the operating system, https://github.com/numworks/epsilon https://github.com/numworks/epsilon
Jyaif 8y ago
This is one of the best crafted website on the internet.
zokier 8y ago
Personally I feel like clamshell design would make lots of sense for these more advanced calculators. At the same footprint you could have lot bigger screen, and more/bigger buttons. As an added bonus the screen would be more readable when sitting on a desk. I wouldn't think the marginally added thikness would impact much something thats being carried around in backbacks most of time anyways. For some reason practically no calculators seem to have used clamshell design. Does anyone know why? Closest example I know of would be HP 200LX, but it is a full-blown computer so it doesn't fit the requirements for education market. Looking at this side by side picture with a graphing calculator, it is not difficult to imagine the calculator keys being transplanted to 200LX to make a nifty new device. https://cdn.pbrd.co/images/HFcfXoM.png https://cdn.pbrd.co/images/HFcfXoM.png
- Ecco 8y ago
  Full-blown qwerty-like keyboards are forbidden for a bunch of standardized tests such as the SAT.
  - zokier 8y ago
    Here is quick mockup of what I was trying to communicate with the last paragraph; 200LX form-factor with calculator keyboard: https://cdn.pbrd.co/images/HFd9eyb.jpg https://cdn.pbrd.co/images/HFd9eyb.jpg Of course the layout needs bit optimization instead of literally just copy-pasting the existing one.
- fmajid 8y ago
  The HP-28C and HP-28S were clamshells, along with their business counterparts. Great calculators, although the 28C was a bit tight on RAM. I had a 28C, 95LX and 200LX. The modern equivalent of the latter would be the Planet Gemini.
- abdulhaq 8y ago
  The problem is that the cabling at the hinge is prone to breaking.
- ReverseCold 8y ago
smartmic 8y ago
If you care about calculation/typing efficiency, you might also want to check out RPN (reverse polish notation). I am recommending the HP 35s. Once you are used to the notation, it is a real pleasure, not only for old-school advocates like me. Added bonus: you will gain respect for stack-based languages like Forth, Factor etc.
- StreakyCobra 8y ago
  I tried the HP35s of a friend for a few days. It is globally a nice RPN calculator and not too expensive for starting. But I don't want to get one because this calculator have a quite long list of known bugs [1] that have been sitting there for more than 10 years now, and HP hasn't fixed anything yet! If you are a grown-up children like me and just want a pretty expensive toy, I can recommend the SwissMicros DM42 [2] (I'm not related to them in any way, just a happy customer). The made an adaptation of the HP42s for the modern world: «34 decimal digits of precision, with exponents ranging from -6143 to +6144», based on the excellent Thomas Okken's Free42 [3], big and nice screen, USB connection for loading/saving programs, save and restore of the calculator state, and so on! And being based on Free42 you can get the emulator on your phone and share the programs with the calculator. You then have the same "calculator" everytime with you, no need to get used to another program/interface on your phone. [1] http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cgi?read=735 http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cg... [2] https://www.swissmicros.com/dm42.php https://www.swissmicros.com/dm42.php [3] http://thomasokken.com/free42/ http://thomasokken.com/free42/
- gh02t 8y ago
  I also use clac on my desktop (https://github.com/soveran/clac https://github.com/soveran/clac). It's a line-oriented RPN calculator like Unix dc, but it shows the stack dynamically as you type. I have a long-term ambition to port it to a physical calculator - either my own design or one like the Numworks or a SwissMicro (a recreation of the HP-42s).
- 8fingerlouie 8y ago
  My trusty companion, when my HP 48G isn't with me, is my 1987 HP 42S. It has been on my desk for around 2 decades. https://en.wikipedia.org/wiki/HP-42S https://en.wikipedia.org/wiki/HP-42S
fmajid 8y ago
No RPN, no deal, sadly. Have a look at the Swiss Micros DM-42L, it's a thing of beauty.
- kwhitefoot 8y ago
  Looks remarkably similar to HP calculators. Is this deliberate and is there some connection between them an HP? If I had just seen the picture and not seen the name on it I would have assumed it was HP.
foolinaround 8y ago
how does this compare in terms of capabilities, prices etc with existing alternatives such as TI, etc?
evan950 8y ago
While the calculator itself seems really cool, I'm really perplexed by this design. I see little point to advertising it as something that can input and execute python if it takes you at least 5 minutes to type `for i in range(10): print(i)`
- mnoronha 8y ago
  I think this tradeoff was to keep it compatible with Collegeboard's (archaic) calculator policies, which forbid keyboards. [1] Being able to market the calculator as SAT-approved is probably super valuable since most students won't buy multiple calculators. [1]: https://apstudent.collegeboard.org/takingtheexam/exam-policies/calculator-policy https://apstudent.collegeboard.org/takingtheexam/exam-polici...
  - redwheelbarrow 8y ago
    It'd be pretty tough to use it on the SAT if you take most of the allotted time trying to type out a function.
    - jedieaston 8y ago
      You can use it just like a TI-84, its just that it uses Python (which programming curriculums in k-12 are increasingly using) instead of TI-Basic.
    - uneekname 8y ago
      While you're right about how long it takes to type a function on a calculator like this, this calculator is a huge step up from the TIs kids use on the SAT right now.
      - redwheelbarrow 8y ago
        That's valid.
- mjs7231 8y ago
  I did this on the old TI-89 back in the day. It was fine for writing physics functions out. If you wanted anything more complex you presumable write the program on another computer and upload it to the calculator.
ju-st 8y ago
Does it run Doom and Pokemon like its TI competitors?
- ivanfon 8y ago
  Found a video of an NES emulator running on it[1], so... Probably. It’s quite a bit faster than the common TIs and Casios. [1] https://www.youtube.com/watch?v=BDVeut56AJU https://www.youtube.com/watch?v=BDVeut56AJU
nicolashahn 8y ago
Virtually everyone that would own one of these already has a smartphone with more computational power, where an app can be made, or already exists, that does all of these functions or more. Is the only reason for this to exist for use on a standardized test?
- uneekname 8y ago
  Not only are standardized tests (and thus preparatory high school tests) stringent against cell phone use, but companies such as TI have had a monopoly on the market for a long time. It's great to see a competitor that uses a more modern underlying language, that costs as much or less than the TIs do. I really hope this calculator or something similar starts to catch on at secondary schools in the U.S.

158 points by 0xb100db1ade 8y ago

"It is also permitted for use on the SAT by the College Board starting with the August 2018 administration." That's ridiculous. Privatized standard testing seems like a bad deal for folks who can't afford these expensive calculators.

madengr 8y ago
I’d hope a calculator is useless for the tests, as they are for most math courses. I’m sure eBay is riddled with these stupid TI type graphing calculators, so anybody can afford one.
marmaduke 8y ago
The point is that schools will only buy bunches of these things for teaching if they’re approved for use on the exams.
- changingmylife 8y ago
  the same schools that can't afford pencils and paper for the students so teachers have to buy supplies out of their own pockets?
- florence123 8y ago
  The point is that it seems flawed that these are approved for exams, not that this isn't a good business decision on the part of the company advertised here.

kfogel 8y ago

It's not open source; the Hacker News headline is wrong. The Numworks web site does not claim it's open source, by the way -- the problem is only in the headline here. The license is Creative Commons Attribution-NonCommercial ShareAlike (CC-BY-NC-SA), and the presence of the "NonCommercial" clause makes it unambiguously non-open-source. If that clause were not present, CC-BY-SA would still be an odd license to use for software anyway, but because of the NC clause we never get to that issue.

marmaduke 8y ago
Source appear to be on GitHub. Non commercial is not incompatible with open source. It makes sense to me that to get the investment required to fund this, you’d want sole rights to commercialize. Nothing prevents someone else from building a cheaper DIY version as long as they don’t sell it. For example it could be a local college class exercise to build these from scratch for local high school. That’s not imaginable for the TI calculators (which these seem to aim to replace)
- kfogel 8y ago
  Source being on GitHub does not equal "is open source". Restrictions on commercial use are incompatible with open source. The Open Source Initiative, which coined the term and evaluates licenses for compatibility with the Open Source Definition (see https://opensource.org/definition https://opensource.org/definition), is crystal clear on this point: if your license has a field-of-use restriction -- such as a restriction on commercial use -- then it's not open source. This is why Numworks is careful not to describe their software as "open source", to their credit.
  - PurpleRamen 8y ago
    It may not be "Free Source", but if the source is open in the sense if being accessable, then for normal people it is open source. One organization using words in a specific way, doesn't negate all other legit interpretations of those words. It's an unsolvable problem they created there.
    - cpks 8y ago
      Nope. Open Source is a trademark precisely to avoid this sort of misuse. It's not a "what it means to whomever" sort of deal. That was done in part due to intentional (and damaging, if ultimately unsuccessful) efforts to undermine the meaning of terms like 'Free Software' by Microsoft back when the FSF was a fledgling movement and Microsoft was an evil empire. I don't mean to imply negative things about the company. The license is still a heck of a lot better than fully proprietary -- I love the product in part for that reason -- but it's definitely not 'open source' or 'free software' as the headline implies. (I don't think the company claims it is either)

dbcurtis 8y ago

It should be pointed out that this is Micropython, not the Python that you are probably used to. Micropython is great stuff, I’m a huge fan, but it is different from CPython in noticeable ways. They seem to have simply copied a source snapshot over; I’m not sure what that means for incorporating updates and fixes to the Python system. Maybe they needed a fork for some reason. I do wish their documentation gave a little more credit to the Micropython project.

tyingq 8y ago
The device does appear to be capable of receiving updates: https://workshop.numworks.com https://workshop.numworks.com Concur on the credit thing though.
- dbcurtis 8y ago
  Yes, you can update the device. My comment was more about how Numworks can practically integrate Micropython updates. It seems like maybe it could be a Git submodule so that changes were easier to merge. Tracking Micropython bug fixes and enhancements is going to be very labor intensive unless I am missing something here. (Admittedly, I didn’t spend a lot of time nosing around Numwork’s source repo. I have spent a lot of time nosing around the Micropython repo to do my own tweaked builds.)

pietroglyph 8y ago

It's always amazed me how, in 2018, TI calculators with software and hardware from 10 years ago still cost $100+ dollars [0] and command a near monopoly in US secondary schools (which, I suppose, is why they still cost that much). For that price you can get a significantly more powerful and functional mobile phone [1] (see 24K of ram vs. 2GB, 96x64 screen vs. 720 x 1280)! The space needs competition, and I hope Numworks gives TI a run for their money (the calculator is even allowed on the big standard exams), but schools are so standardized on TI calculators (and generally slow-moving) that change will be hard. Casio has also tried to break into this space with significantly cheaper calculators (which are also allowed on standardized exams), but they have failed to gain significant traction so far. A relevant XKCD (of course): https://xkcd.com/768/ https://xkcd.com/768/ A related piece of journalism: https://wapo.st/1Cl0Vyf https://wapo.st/1Cl0Vyf [0]: https://www.amazon.com/dp/B0001EMM0G/ https://www.amazon.com/dp/B0001EMM0G/ [1]: https://www.amazon.com/dp/B01H2E0KVA/ https://www.amazon.com/dp/B01H2E0KVA/

fafner 8y ago
More like hardware from 20 years. Yeah I hope the TI monopoly gets broken. Numworks looks exactly like the calculator I was dreaming about when I was in uni.
- craftyguy 8y ago
  Actually, more like hardware from 40 years ago. The Z80 processor was released in like the mid 70s.
qubex 8y ago
I’ve been using both a Texas Instruments Nspire and an HP Prime, and I definitely find the latter to be preferable as it’s leaps and bounds beyond the former in terms of symbolic algebra.
escherplex 8y ago
Agree with you there. You may have habituated to TI-89s back at school (still have two) but by today's standards, graphics are super low-res and UI reminds you of trying to manipulate a rubik's cube. And yet it's still a goto on Amazon for about US$140.

Ecco 8y ago

You may want to check out: The whole calculator running in a browser, thanks to emscripten : https://www.numworks.com/simulator/ https://www.numworks.com/simulator/ An interactive PCB viewer, in the browser again : https://www.numworks.com/resources/engineering/hardware/electrical/pcb/ https://www.numworks.com/resources/engineering/hardware/elec... Full schematics https://www.numworks.com/resources/engineering/hardware/electrical/schematics/ https://www.numworks.com/resources/engineering/hardware/elec... And of course the whole source code to the operating system, https://github.com/numworks/epsilon https://github.com/numworks/epsilon

Jyaif 8y ago

This is one of the best crafted website on the internet.

zokier 8y ago

Personally I feel like clamshell design would make lots of sense for these more advanced calculators. At the same footprint you could have lot bigger screen, and more/bigger buttons. As an added bonus the screen would be more readable when sitting on a desk. I wouldn't think the marginally added thikness would impact much something thats being carried around in backbacks most of time anyways. For some reason practically no calculators seem to have used clamshell design. Does anyone know why? Closest example I know of would be HP 200LX, but it is a full-blown computer so it doesn't fit the requirements for education market. Looking at this side by side picture with a graphing calculator, it is not difficult to imagine the calculator keys being transplanted to 200LX to make a nifty new device. https://cdn.pbrd.co/images/HFcfXoM.png https://cdn.pbrd.co/images/HFcfXoM.png

Ecco 8y ago
Full-blown qwerty-like keyboards are forbidden for a bunch of standardized tests such as the SAT.
- zokier 8y ago
  Here is quick mockup of what I was trying to communicate with the last paragraph; 200LX form-factor with calculator keyboard: https://cdn.pbrd.co/images/HFd9eyb.jpg https://cdn.pbrd.co/images/HFd9eyb.jpg Of course the layout needs bit optimization instead of literally just copy-pasting the existing one.
fmajid 8y ago
The HP-28C and HP-28S were clamshells, along with their business counterparts. Great calculators, although the 28C was a bit tight on RAM. I had a 28C, 95LX and 200LX. The modern equivalent of the latter would be the Planet Gemini.
abdulhaq 8y ago
The problem is that the cabling at the hinge is prone to breaking.
ReverseCold 8y ago

smartmic 8y ago

If you care about calculation/typing efficiency, you might also want to check out RPN (reverse polish notation). I am recommending the HP 35s. Once you are used to the notation, it is a real pleasure, not only for old-school advocates like me. Added bonus: you will gain respect for stack-based languages like Forth, Factor etc.

StreakyCobra 8y ago
I tried the HP35s of a friend for a few days. It is globally a nice RPN calculator and not too expensive for starting. But I don't want to get one because this calculator have a quite long list of known bugs [1] that have been sitting there for more than 10 years now, and HP hasn't fixed anything yet! If you are a grown-up children like me and just want a pretty expensive toy, I can recommend the SwissMicros DM42 [2] (I'm not related to them in any way, just a happy customer). The made an adaptation of the HP42s for the modern world: «34 decimal digits of precision, with exponents ranging from -6143 to +6144», based on the excellent Thomas Okken's Free42 [3], big and nice screen, USB connection for loading/saving programs, save and restore of the calculator state, and so on! And being based on Free42 you can get the emulator on your phone and share the programs with the calculator. You then have the same "calculator" everytime with you, no need to get used to another program/interface on your phone. [1] http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cgi?read=735 http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cg... [2] https://www.swissmicros.com/dm42.php https://www.swissmicros.com/dm42.php [3] http://thomasokken.com/free42/ http://thomasokken.com/free42/
gh02t 8y ago
I also use clac on my desktop (https://github.com/soveran/clac https://github.com/soveran/clac). It's a line-oriented RPN calculator like Unix dc, but it shows the stack dynamically as you type. I have a long-term ambition to port it to a physical calculator - either my own design or one like the Numworks or a SwissMicro (a recreation of the HP-42s).
8fingerlouie 8y ago
My trusty companion, when my HP 48G isn't with me, is my 1987 HP 42S. It has been on my desk for around 2 decades. https://en.wikipedia.org/wiki/HP-42S https://en.wikipedia.org/wiki/HP-42S

fmajid 8y ago

No RPN, no deal, sadly. Have a look at the Swiss Micros DM-42L, it's a thing of beauty.

kwhitefoot 8y ago
Looks remarkably similar to HP calculators. Is this deliberate and is there some connection between them an HP? If I had just seen the picture and not seen the name on it I would have assumed it was HP.

foolinaround 8y ago

how does this compare in terms of capabilities, prices etc with existing alternatives such as TI, etc?

evan950 8y ago

While the calculator itself seems really cool, I'm really perplexed by this design. I see little point to advertising it as something that can input and execute python if it takes you at least 5 minutes to type `for i in range(10): print(i)`

mnoronha 8y ago
I think this tradeoff was to keep it compatible with Collegeboard's (archaic) calculator policies, which forbid keyboards. [1] Being able to market the calculator as SAT-approved is probably super valuable since most students won't buy multiple calculators. [1]: https://apstudent.collegeboard.org/takingtheexam/exam-policies/calculator-policy https://apstudent.collegeboard.org/takingtheexam/exam-polici...
- redwheelbarrow 8y ago
  It'd be pretty tough to use it on the SAT if you take most of the allotted time trying to type out a function.
  - jedieaston 8y ago
    You can use it just like a TI-84, its just that it uses Python (which programming curriculums in k-12 are increasingly using) instead of TI-Basic.
  - uneekname 8y ago
    While you're right about how long it takes to type a function on a calculator like this, this calculator is a huge step up from the TIs kids use on the SAT right now.
    - redwheelbarrow 8y ago
      That's valid.
mjs7231 8y ago
I did this on the old TI-89 back in the day. It was fine for writing physics functions out. If you wanted anything more complex you presumable write the program on another computer and upload it to the calculator.

ju-st 8y ago

Does it run Doom and Pokemon like its TI competitors?

ivanfon 8y ago
Found a video of an NES emulator running on it[1], so... Probably. It’s quite a bit faster than the common TIs and Casios. [1] https://www.youtube.com/watch?v=BDVeut56AJU https://www.youtube.com/watch?v=BDVeut56AJU

nicolashahn 8y ago

Virtually everyone that would own one of these already has a smartphone with more computational power, where an app can be made, or already exists, that does all of these functions or more. Is the only reason for this to exist for use on a standardized test?

uneekname 8y ago
Not only are standardized tests (and thus preparatory high school tests) stringent against cell phone use, but companies such as TI have had a monopoly on the market for a long time. It's great to see a competitor that uses a more modern underlying language, that costs as much or less than the TIs do. I really hope this calculator or something similar starts to catch on at secondary schools in the U.S.