My thoughts are that standardized tests will still miss a lot of people. Some people just don't approach tests in the correct way.
If there were a test I believe having a building that had all kinds of different activities in it from musical instruments, labs, computers, rooms with books on different topics, and other activities.
Drop the children off there and tell them to have fun. Observe. Look for that spark of excitement. Make note of this.
Then try exposing them to more of that which seemed to excite them. Repeat this process several times. Sometimes perhaps with a group of kids, and other times solo in case they are self conscious and to avoid bias due to trying to fit in.
My thought was to present a child with as many opportunities as possible so we can hopefully catch that SPARK. That thing that they are passionate about, or several things.
Even with this method we'd likely still miss some students. So it is possible this combined with the other methods might even get a better cross section.
Yet, instilling the child with a love of learning is key. Forcing them into a mold doesn't seem to usually do this.
I love to learn but honestly I was a bad student. So I can relate to this. I did find several passions and I found them ALL outside of school. I found them early enough that this is partially why I was a bad student. I did just enough to get by in class and in the meantime I was filling up notebooks and teaching myself things they didn't teach in school.
I was a programmer before it became an in thing. I also sucked at English until my final year of high school though I read, and wrote a lot. It took a creative writing class with a good teacher that tossed out the rules for me to finally GET English in a way that worked for me. I never had any problems with any English, Creative Writing, etc after that. I simply didn't fit into the mold they spent 11 years prior to that trying to shove me in. I literally had some Fs and Ds in English. 12th grade I did something different and never got anything less than an A in any English related class including college after that. What's worse is I hardly had to try to get that A. So it turns out I did have a passion there too, but I despised the approach they'd been trying to force on my for 11 years. Who knew? I didn't.
My passions at that age were computer programming, music, and writing. I read a ton as well on all kinds of subjects and they rarely had anything to do with any actual class work.
I have some bright kids too. I actually witnessed the current system sucking the love of learning out of them and trying to conform them into a standardized form. It actually damaged a natural ability my youngest son had. My kids loved learning... for awhile... no child left behind amounted to all kids taught the same speed and they eventually grew bored.
I eventually did something about this, but I waited a bit too long. I bought into the Appeal to Tradition bullshit even though what we have as education now is nothing like it was for me as a child. It is worse.
I suppose what you propose would be what the entirety of kindergarten should be about. Learning through various methodologies and then suggesting the best school for each individual based on what makes them spark.
I was thinking in a more middle-high school approach since thats what I taught. By that point it would probably be too late.
I also failed in school - in fact by the end I just stopped turning up and went to the park every day instead. Failed miserably. But I went to a music college which got me into University studying music, and here I excelled and my passion for life was born. At this point, where education became a choice, I started finding passion for science, literature, gardening, painting, you name it.
So you're definitely on the right track, but realistically, it ain't happening any time soon. Here in China, students are so focussed on getting A's that the actual journey to that grade is irrelevant.
Students trying to go to America for example who do the SAT exam will more than likely get a call saying 'I'm sorry, but too many students cheated so the exams are all void' (Actually happened in the school I taught in).
Bribery and plagiarism is rife here, because they've somehow learnt that the actual process of learning is obsolete, and we can all be experts if we have enough money. Sigh.
No I'd propose doing it at different ages to see if interests change, and expose people to opportunity at different age levels. The key is giving people opportunity to hopefully be exposed to the thing they are interested in. Many things would not be something a kindergarten student would likely know yet that they have an interest in.
I only ever took ONE class my senior year that was music related K-12. I told you one of my passions was music. I played guitar, and I composed electronic music very early in that process. All which was self taught.
When I went to college the college I went to lied about having a Computer Science major when I got there so I was initially a dual Physics/Music major and the music was primarily so I could take the music theory and other classes I was interested in without being told they were not for me. Even in college I was eclectic and very much doing my own thing. I did play Cello (very little) in college.
I learned a lot of interesting things in college, but as with High School the bulk of what I learned was learned on my own outside of classes. I took heavy advantage of the library, computer labs, etc.
I played in the college jazz band for a bit so I'd be exposed to that.
Ultimately I worked on helping that college create the Computer Science major for there. Some of the students teaching Computer Labs were taught more by me than they were their classes. I spent a huge amount of time using the mainframe, and exploring the early internet pre-WWW.
Yeah I know. :) I don't usually bother to write about east projects. :P
That is happening in the U.S. too, but they try to pretend it is not. That is where my reference to sometimes thinking people got their degree out of a cracker jacks box came from.
I believe a large amount of the population actually never finds what they are passionate about. They just plod along and follow what they've found works within the system.