Makenzie Hymes was so heartbroken by the latest shooting at a US school she decided to prepare an Australian history lesson for American politicians.

Hymes, a 13-year-old who loves dancing and the piano, wrote the story of Australia's gun control laws on a placard she took to the White House this week where she joined dozens of other school children demanding tougher gun laws.

Most students kept to short slogans.

"Am I next?" read one.

"Fear has no place in school," said another.

But Hymes, a middle school student in Washington DC, wanted Americans to know about John Howard's response to the Port Arthur massacre more than two decades ago.

"Australia had its worst mass shooting on April 28, 1996," her placard read, before explaining the bipartisan deal that followed.

"The government brought back and destroyed over one million guns," she concluded. "Australia has not had a mass shooting since then."

Students like Hymes have led the protests against existing US gun laws over the past week, in the wake of the mass shooting at a Florida high school that left 17 dead.

The teenage killer used an AR-15 assault rifle, the weapon used in five of the six deadliest US shootings in recent years including those in Las Vegas, Sandy Hook and Orlando. The weapon is banned in Australia outside military use.

Hymes was one of the younger protesters at the rally on Monday, timed for the President's Day public holiday to maximise attention on Donald Trump's refusal to consider tougher laws.

Flags flew at half-mast on federal buildings, including the White House, to honour those who died in Florida.

"I feel like if people hear about what other countries do they'll realise we're a lot behind," Hymes told Fairfax Media when asked why she wanted her fellow Americans to learn from Australia.

"It's not impossible to change things, it's not stupid. Various foreign countries like Australia have done things to get rid of the bad guns. I don't know much about what Australia did, but I know that they got what they needed sooner rather than later."

The White House protest was relatively small, with about 50 students attending, and there is no sign of widespread momentum for reform. While Australia struggled to achieve change across six states, the US faces the challenge of reaching deals across 50 of them.

But there is real frustration among young Americans who feel their elders are not doing enough to make schools safe. The organisers of this week's protests, Teens for Gun Reform, are planning a march on Washington on March 24.