From an older answer on the topic, to "In 2018, 17 years after 9/11, every school in America holds commemorations. Did they do that for Pearl Harbor in 1958?":

Commemoration of Pearl Harbor in 1958 was not forgotten, although having fallen on a Sunday that year while commemorations happened, they would have not impacted the school day. Reading up on how the day was observed though, it is fairly interesting to see the differences and similarities, since while they did happen, they were quite muted in comparison with more modern 9/11 commemorations. In the New York Times, it was noted that State buildings in New York would fly at half-mast for the morning, to symbolize the tragedy of the attack, and be raised to full-staff at noon, "symbolizing final victory". It having fallen on a Sunday, many religious services were centered on remembrance that day, but as far as civic ceremonies went, they were decidedly smaller than we see with 9/11, and less publicized.

In Pearl Harbor itself, a small memorial service was planned. Some family members were in attendance, but it was a fairly subdued affair. The USS Arizona Memorial now there was not yet built (coincidentally, it was authorized by Congress that year though), and the ceremony was held on a small, purpose built wooden platform. Three prayers by Naval chaplains were the only speeches given at the remembrance held on a platform before the wreck of the USS Arizona, which had no oration, and was followed with the placing of a dozen flower arrangements placed at the flag staff of the ship. Music was played by a band on Ford Island nearby while the flag was then raised. Although not part of the ceremony itself, the USS Bennington passed by the wreck that day as well in tribute, with the sailors and airmen spelling out "ARIZONA" on the ship's flight deck.

Near Washington, DC, a memorial was held at Arlington National Cemetery's Tomb of the Unknown Soldier, led by Leo Hoegh, the head of the Office of Defense and Civilian Mobilization, although in a theme which we will return to, his remarks were quite expected:

The greatest tribute we can pay those who have fallen in the defense of our country and in particular those who fell on this day in 1941 is the solemn pledge that never again will we be caught unprepared by a surprise attack.

In New York City, and others communities as well, the biggest city-wide gesture was a three minute blast of the air-raid siren, timed in New York at least for 2 pm, or roughly when the city had heard that the attacks were happening in 1941. "A three-minute rising and falling sound" was played - the signal to seek shelter - to then be followed by a steady sound for three minutes at 2:10, the signal to receive instructions via radio. The public wasn't required to actually go to shelters, and traffic was not even stopped. Although there was no school that day, as that is something specific you are interested in, I would also note here that in later years, "Take Cover" drills were not required to happen, but in years where school was in session, the students would in some cases participate and use the sirens as a signal to 'duck and cover'. An article from 1960 also notes that this wasn't entirely popular though, and that "'Students for the Abolition of Civil Defense Drills' took part in the drill, but worse armbands as a sign of protest" at the Evander Childs High School in the Bronx.

This helps to illustrate the context in which remembrance of Pearl Harbor was understood in that time, a period of rising fears the existential threat of nuclear war as the Cold War dominated the stage. The US had had a clear lead in is nuclear arsenal originally, but fears that the Soviets were closing in were rampant, and of course while actual numbers were not as high, public perception of the so-called "Missile Gap" was first starting up at that point, and whether true or not (it wasn't), it did help lend itself to renewed emphasis on the need for public awareness of how to prepare for and react to Armageddon.

The US Air Force's Continental Air Command held an exercise at Mitchel AFB on the presumption of a detonation of a nuke on Wall Street, and the Air Defense Command displayed five missiles in Washington Square Park for the day. In fact, 1958 is actually particularly notable as it was the first celebration of "National Civil Defense Day" which was pegged to Dec. 7th, and Director Leo Hoegh's remarks on the inaugural commemoration remembered Pearl Harbor as something that "will stand out through our history as a tragic reminder of the tremendous consequences of unpreparedness". For a commemoration aired on television that day, Maj. Gen. Robert Berry - Air Defense Command regional Commander for the area including Pearl Harbor - discussed how prepared the US was to meet a Soviet attack and that "I think that this is one of the few times in history when the defense is superior to the offense". In a similar radio interview, the Sec. Navy, Thomas Gates also stressed how strong the US military was, and that it would be impossible now to conduct a similarly crippling attack.

Veterans organizations, especially American Veterans of World War II and Korea which routinely organized memorial exercises on Pearl Harbor Day also made sure to harp on this message in how they observed the day. The groups commander, Dr. Winston E. Burdine noted that:

Once again, Dec. 7 falls on Sunday, as it did on that fateful date in 1941. The world situation still is extremely tense and, in this age of missiles and rockets, surprise attack could spell devastation. [...] It is our hope that observance of Pearl Harbor Day will serve to make the public aware of the significance of Pearl Harbor and the importance of defense mobilization.

He went on to note additionally that AMVETS would provide free civil defense material to any persons who wrote their DC HQ requesting them. Even the religious observances mentioned made civil defense an important focus of their sermons, such as noted by Rabbi Dr. Norman Salit, who noted that "It is high time for the American people to become mature in the presence of this dread peril and make civil defense more than an empty phrase".

The New York Times itself devoted a short item in the editorial section to the phrase "Remember Pearl Harbor", tying it into the nuclear test ban conferences then being held at Geneva, where it was being felt that the Soviets were blocking progress, which I will excerpt:

We can, however, remember Pearl Harbor in quite a different sense. The mistake of the Japanese militarists that prompted the attack was the misinterpration of the free discussion and the obvious differences of opinion in this country that preceded it. It was assumed that one great and mischievous blow would reveal deep fissions in our body politic and that we would be confused, irresolute and divided. No greater mistake could have been made. Pearl Harbor was the huge galvanic shock that made us one people in one cause, determined and invincible. [...]

Let us hope that we will never again be confronted with a similar crisis. But let us also be aware that there are other great challenges to our strength and resolution that will be put before us. These can be the challenges of peace, of progress, of intelligence and of humanity. On this ground there are greater battles to be fought than any Pearl Harbor. Let us remember that we can fight them in united courage.

Other papers ran similar features, such as the L.A. Times, which reminded its readers "At that time Japanese militarists were threatening Thailand; today the Soviets are threatening us and the free world in Berlin and are addressing us with ultimatums".

So the basic take away that one should have is that while "Remember Pearl Harbor" was a phrase that was followed, it was, in that period, not one remembered with too much somber reflection, but rather as an exhortation against complaisance. Civil, military, and private interests all used it as a rallying cry for preparedness, and that the costs were much, much higher this time. As Guy Oakes notes on the mood of the time:

In December 1941, the United States had risked defeat in the Pacific by failing to prepare for war. In the Cold War, the stakes were immeasurably higher the margins of error narrowed to the vanishing point. By failing to prepare for nuclear war, the United States risked much more than a military defeat: It stood to loose everything.

As such, commemoration was mostly a mix between extolling America's strength to survive such an attack, but nevertheless the vigilance to be ready and prepared for if it happened anyways. Just about the only memorial which I can find mention of that didn't include this focused theme of national readiness, in fact, was that held at Pearl Harbor itself, the prayers offered being more in line with that of Capt. Roland Faulk, who spoke of the holy ground (holy waters?) where the fallen sailors now were entombed, "[made holy] by the sacrifice and death of a gallant company who, standing to their duty in the time of danger, stood firm to the end." Not to say other similar ones didn't happen, but they didn't make headlines. Nor is any of that is of course to say those sentiments were included, or even central, in other commemorations, but it is clear enough that talk of their sacrifice was generally transitioned to how not to let it have gone in vain.

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