The parashah begins with the words (21:1), אליהם ואמרת אהרן בני הכהנים אל אמור, "Say to the kohanim, the sons of Aharon and say to them..." The word "say" (ואמרת ...אמור) is written twice in this sentence.
Rashi explains, הקטנים על גדולים להזהיר, "The older kohanim should train the younger kohanim." הכהנים אל אמר, "Tell the older kohanim... אליהם ואמרת, to train the younger kohanim" to be cautious with the unique laws of kehunah.
This pasuk demonstrates the ideal chinuch, that the older kohanim should train the younger ones. Therefore, we can glean guidance in chinuch habanim from this parashah.
A fundamental rule in chinuch is to be a role model. More than words, parents teach by example. We can learn this from Avraham Avinu, as it states (Bereishis 18:7) אברהם רץ הבקר ואל אותו לעשות וימהר הנער אל ויתן וטוב רך בקר בן ויקח, "Avraham ran to the cattle, took a tender and good calf, and gave it to the youth who hurried to prepare it."
Rashi writes that the lad was Yishmael. Avraham wanted Yishmael to prepare the meat for the guests במצות לחנכו כדי, to train him to do mitzvos. But Avraham himself brought the calf. He didn't send Yishmael to bring the cattle, he only had him prepare it. This is because the best way to educate children is by example. Yishmael saw his father rush to get animals for the guests (as it states רץ הבקר ואל אברהם), and then Yishmael, too, prepared them quickly (as it states אותו לעשות וימהר, "he hurried to prepare it"). He learned from his father's example.
B'derech remez, we can say that Rashi is hinting at this lesson when he writes (21:1) הקטנים על גדולים להזהיר. This can be translated as גדולים להזהיר, the adults' deeds and their good ways should shine and influence, הקטנים על, the younger generation.
This is why the masechta on good middos is called Pirkei Avos, Chapters of the Fathers. One of the most effective ways to train children is for the parents themselves to act in the manner that they want their children to behave.
Chazal (Bava Kama 97:) say, "What coin did Avraham Avinu have? There was an old man and an old woman on one side of the coin and a lad and a girl on the other." The old and the young are on two sides of the same coin, indicating that the young are influenced by the old.
Rashi (Bereishis 12:3) writes, "A father says to his son, 'You shall be like Avraham.'" We can explain (צחות בדרך) that parents want their children to be like Avraham Avinu, but they don't want to live that way themselves. They want to live like Avraham's father, Terach and hope their children will turn out well. It doesn't work that way. The parents must work on themselves first, and then their children will follow suit.
Reb Yaakov Galinsky zt'l told the following mashal: There was a non-Jew who pretended to be a Jew so he could go around the batei midrashim, collecting money during the tefillos. One day, he heard one of the collectors announce, "Raboisai! I’m a ger tzedek. The Torah says forty-eight times that one must love converts!" and everyone gave him generously. Another day, he heard someone announce that he was a descendant of the Baal Shem Tov zt'l and saw how people gave generously to him. So, the goy announced, "I’m an einekel of the Baal Shem Tov, and I’m a ger tzedek." He was quickly banished from the beis medresh since his words contradicted and nobody believed him.
Reb Yankele Galinsky zt'l says that the same is true when parents tell their children to act a certain way but don't practice what they preach. They are contradicting themselves, so their words are ineffective. Reb Yankele also applied this to public speakers (darshanim). If they speak about things that they themselves don't do, their words won't take effect; their deeds contradict their words.
Pirkei Avos often states, אומר היה הוא, "He would say..." We can explain הוא, his essence, אומר היה, is what he spoke. When one talks about middos and yiras Shamayim, and that is who he is, such words will influence children to go on the good path.
