The thing about "weed-out" classes is that they're in some respects indiscriminate--to extend the metaphor, they sometimes spray so much curricular pesticide that they wipe out many people who might either *eventually* find the core skills and methods congenial or they underimagine what the core skills being laid out actually are in relationship to all the professional activities that have some relationship to that core.
The former point has become more and more intense for me over the years--as STEM departments have been under pressure to improve outcomes for underprepared students and to make their majors more inclusive, there have been more students who survive a "weed out" despite receiving poor grades in the lower rungs of the curricular hierarchy and maybe only barely making it through the major at all only to flourish spectacularly at a later date in a professional or scholarly role that rests on their undergraduate education. It means there really shouldn't be courses that are impassable barriers, especially in terms of what you're suggesting here--that since you can't have students engaged in the actual practice of a STEM field before they have the necessary preparation, you have to give them some feel for how challenging that practice is going to be, whereas many of the humanities and social sciences can set students to actual practice of their fields and disciplines from the get-go and just help them become more and more sophisticated in that practice over time.
But I also think many STEM faculty under-imagine what those end-state professional practices are in relationship to the discipline that they themselves work with. The relationship between primary care medicine and biology/biochemistry is more distant than a lot of faculty credit; the notion that organic chemistry is giving premed students a challenging window into their professional future and letting them decide whether they're going to find that life congenial just seems empirically untrue. If I really wanted to "weed out" future doctors before they get themselves deep in debt and find it's not the life they wanted, I'd compel them to endure the terrible conditions facing many residents, I'd have them deal with insurance adjusters telling them what they can and cannot offer as a standard of care, I'd have them spend a day listening to patients of all temperaments and presentations, and I'd have them spend a Saturday night in a crowded underfunded urban emergency room. The notion that organic chemistry is a good proxy test of what life as a basic physician (or other health-care professional) will be like just seems wrong. I think we try to tell ourselves that our assessments are good predictions of later professional competency, and I think for our own disciplines, that's absolutely true. I cannot imagine that someone who profoundly hated physics (or history) could perservere and become a skilled scholarly physicist or historian. But I can imagine someone surviving biology enough to do any number of jobs where biological science is somewhere present but not determinative of everyday professional practice. In some cases, this is not at all hypothetical--there's tons of evidence that barely-passing CS majors may end up being enormously successful tech designers or executives, barely-passing engineers may end up flourishing in industry or policy, etc.
I agree with you that STEM fields do build on foundations, which end up serving as weed out classes. That being said, I also think the way of teaching physics that I experienced was designed for future physicists and not for a broader audience (eg. Engineers, other majors taking intro Physics). They often dove into the math rather than taking the pains to explain how it connects to real life.
Moving further into the course, us experimentalists experienced something similar from courses taught by theoreticians. For instance, we were taught Jackson, without explaining why and when the formal framework is needed. I finally got "weeded out" when I went for a QFT course in grad school, and even the first lecture wasn't explained in a way I could understand.
In professional life, I have found people of all backgrounds pick up a working knowledge of almost anything that relates to what they do. I think physics education has a lot of opportunity to make it more accessible to a wider audience.
The thing about "weed-out" classes is that they're in some respects indiscriminate--to extend the metaphor, they sometimes spray so much curricular pesticide that they wipe out many people who might either *eventually* find the core skills and methods congenial or they underimagine what the core skills being laid out actually are in relationship to all the professional activities that have some relationship to that core.
The former point has become more and more intense for me over the years--as STEM departments have been under pressure to improve outcomes for underprepared students and to make their majors more inclusive, there have been more students who survive a "weed out" despite receiving poor grades in the lower rungs of the curricular hierarchy and maybe only barely making it through the major at all only to flourish spectacularly at a later date in a professional or scholarly role that rests on their undergraduate education. It means there really shouldn't be courses that are impassable barriers, especially in terms of what you're suggesting here--that since you can't have students engaged in the actual practice of a STEM field before they have the necessary preparation, you have to give them some feel for how challenging that practice is going to be, whereas many of the humanities and social sciences can set students to actual practice of their fields and disciplines from the get-go and just help them become more and more sophisticated in that practice over time.
But I also think many STEM faculty under-imagine what those end-state professional practices are in relationship to the discipline that they themselves work with. The relationship between primary care medicine and biology/biochemistry is more distant than a lot of faculty credit; the notion that organic chemistry is giving premed students a challenging window into their professional future and letting them decide whether they're going to find that life congenial just seems empirically untrue. If I really wanted to "weed out" future doctors before they get themselves deep in debt and find it's not the life they wanted, I'd compel them to endure the terrible conditions facing many residents, I'd have them deal with insurance adjusters telling them what they can and cannot offer as a standard of care, I'd have them spend a day listening to patients of all temperaments and presentations, and I'd have them spend a Saturday night in a crowded underfunded urban emergency room. The notion that organic chemistry is a good proxy test of what life as a basic physician (or other health-care professional) will be like just seems wrong. I think we try to tell ourselves that our assessments are good predictions of later professional competency, and I think for our own disciplines, that's absolutely true. I cannot imagine that someone who profoundly hated physics (or history) could perservere and become a skilled scholarly physicist or historian. But I can imagine someone surviving biology enough to do any number of jobs where biological science is somewhere present but not determinative of everyday professional practice. In some cases, this is not at all hypothetical--there's tons of evidence that barely-passing CS majors may end up being enormously successful tech designers or executives, barely-passing engineers may end up flourishing in industry or policy, etc.
I agree with you that STEM fields do build on foundations, which end up serving as weed out classes. That being said, I also think the way of teaching physics that I experienced was designed for future physicists and not for a broader audience (eg. Engineers, other majors taking intro Physics). They often dove into the math rather than taking the pains to explain how it connects to real life.
Moving further into the course, us experimentalists experienced something similar from courses taught by theoreticians. For instance, we were taught Jackson, without explaining why and when the formal framework is needed. I finally got "weeded out" when I went for a QFT course in grad school, and even the first lecture wasn't explained in a way I could understand.
In professional life, I have found people of all backgrounds pick up a working knowledge of almost anything that relates to what they do. I think physics education has a lot of opportunity to make it more accessible to a wider audience.