Chinuch has not changed over the generations, that is, the chomer, the substance of chinuch has not changed, but the tzurah, the strategies and methods that convey that substance, has indeed changed and evolved. (This is clear from the Gemara in Baba Basra (21a) that details the different t’kufos of how chinuch was disseminated.)
Rav Yakov Kaminetzky zt”l says that the goal of chinuch is that people should observe the Torah.Chinuch means giving a child the tools to function as a frum Jew in society. It means preparing him to fulfill the mitzvos and keep the Torah and to connect him to Har Sinai, to mesorah as a link in the chain.
What is the role of a mechanech? The role of a mechanech is to be like the Levi’im:
אשריכם שנתמניתם משמשים למקום. “You are fortunate that you are appointed ministers (mishamshim) to Hashem.” But a “shemesh” is also a sun. A sun has many functions: to emit light and heat, to demonstrate the ability for growth, and to serve as an example for times and seasons.
So, too, parents and mechanchim have to enlighten their children and students. They have to warm them up with emotion. They have to give them the ability to grow. And to set an example for them so they know how to act and behave during various times and situations throughout life.
This has always been true, but the tzura, the strategy, has changed over the generations.
We learn in the parashah ביום הזה באו מדבר סיני. Rashi brings a Chazal that says that we learn from the pasuk that we have to learn the Torah every day as if we were given it that day.
But the Torah wasn’t given that day. Nor was the process of starting to give the Torah done on that day. The Jews were tired and wanted to unpack. Hashem only started the process of giving us the Torah on the second day of Sivan. So how can Chazal say that we learn from Rosh Chodesh Sivan that we have to learn Torah every day as if we learned it that day when we didn’t even get the Torah that day?
I think that the lesson here is that Hashem would have loved to start the process of giving the Torah as soon as possible, i.e. from Rosh Chodesh. He had been waiting for this since before the creation of the world!
Nevertheless, before the giving of the Torah, He needed the right conditions, the right amount of people, the right place. Only when everything was perfect, and all the conditions were met could the Torah be given. However, Hashem assessed the situation and saw that the Jews were tired and that it would be counterproductive to give them the Torah that day. So too, a person has to reassess his relationship to the Torah (not the Torah itself) anew each day, to know what fits that day, that time, in those circumstances.
An example: the Michtav M’Eliyahu says that every generation has its own yetzer hara. During the Rambam’s generation, the yetzer hara was Greek philosophy. So, in response, the Rambam wrote מורה נבוכים to combat it.
If you think that chinuch doesn’t change, then the way to fight the yetzer hara today would be to teach Morah Nevuchim. However, the way to be mekarev Jews is not by reading to them Moreh Nevuchim because the yetzer hara of this generation is a different yetzer hara, and there is a different way to fight it. The Torah hasn’t changed but the way to deal with it has changed.
So too with Chinuch Banim, we have to know what is appropriate for the present time and circumstances.
Rav Chaim Shmuelevitz zt”l says, we are told that you go to השופט שבימיך, “the shofet of your generation.” He says that it’s not a bdieved, that really, it would be ideal to go to the Vilna Gaon, but we can’t since he’s not around.
The optimal way, says Rav Chaim is that you have to go to someone who understands your generation, who knows the situation of your generation. Only someone who knows your generation can tell you according to Daas Torah which forms of chinuch will help achieve chinuch. The substance of chinuch doesn’t change, but the form changes. And the gedolim of each place and each time decide which forms of chinuch will bring the substance at that time.