Can minors in CA carry a pocket knife legally?

Yes.
In fact, there is no restriction on blade length either, so you can carry as large knife as you wish. I often carry a folding knife that has a 5.5 inch blade! Also, you can carry your pocket knife in your pocket; that is, concealed. This is a thing that I do every day, and sometimes two or more knives, but I am no longer a minor, and I do not attend school (see below.) I should mention that I live in California, so I have some familiarity with this topic.
However, be wary that any fixed blade knife, no matter how small it may be, must be carried in plain sight. So, for example, boot knives are right out! If you do carry a fixed blade knife, for example in a sheath on your belt, and you are also a minor, be prepared to have people look at you strangely, and to also perhaps be detained briefly by a cop who will ask you a bunch questions even though what you are doing is totally legal. This *could* lead to the cop finding an excuse to search you, or make you turn your pockets out. If this happens, and the cop discovers anything else unusual, perhaps a little weed for example, then you will be detained for a longer time and in a different location such as a jail. When I was a youngster, I personally experienced some unsatisfactory encounters with the local cops, once having my car completely tossed for no reason at all, so I learned that it won’t matter if you feel that you are well within the law, they are still going to do what they want to do.
A potentially big caveat is that nobody, minor or otherwise, can carry any kind of knife into certain government buildings; for example, courthouses (jury duty included), and schools. Private and charter schools will most likely have the same rules.
If you are a minor who also attends a public school, it is advisable to make certain that you do not have a knife on your person, backpack, purse, locker, or even in your car if it is parked in the school lot.
We currently live in a time where the school administrators or teachers, if they were to discover a knife in any of the above locations, might (probably) exhibit an enormously huge level of stupid and do something extreme like call the cops who will put the school on lockdown, which will last the rest of the day while they search every locker in the school and examine every student to see if there are any additional knives anywhere, and of course you will be in a pallet-load of trouble. Also, every student in the school will know that you were the one who made all of them go through a bunch of crap, and that might turn out to be an issue for you.
If you have read this far, I congratulate you for having endured what is probably more information than you wanted, heh heh. I *do* hope that I have answered the question so that your time was not wasted.
Finally, please do not let my comments dissuade you from carrying a knife or two; it is an honored American tradition, and it is useful to have a cutting tool at your disposal should the need arise.

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