"Weather is chaotic," said Melissa Lau, a sixth-grade teacher in this bedroom community outside of Oklahoma City. "What does that mean to you?"

Another boy addedf: "It's another word for 'crazy. My sister got hit by a golf-ball-sized piece of hail."

The students didn't know it yet, but they were about to engage in some myth-busting about perhaps the biggest menace to their futures: climate change.

Ms Lau, 42, has taught science for seven years at Piedmont Intermediate School, which is housed in an airy, modern building overlooking a wheat field and serves predominantly middle-class families, many of whom work in the oil and gas industry. For much of that time, she has sought to acquaint students with the basics of the planet's warming.

On this next-to-last week of the school year, she was squeezing in a lesson exploring the link between increased carbon emissions and extreme weather events such as floods and hurricanes.

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A goal was to give students the knowledge to debunk the argument often made by climate change deniers that a few frigid days disprove climate change; even in a warming climate, there will still be many cold days.

Schools across the United States are wrestling with how to incorporate the study of climate change into the classroom as its proximity and perils grow ever more apparent. According to a recent NPR/Ipsos poll, 86 per cent of teachers and more than 80 per cent of parents say the subject should be taught in school.

But survey results in 2016 showed that while three-quarters of science teachers said they included lessons about climate change, they devoted little time to it and faced an array of obstacles.

The science behind climate change is complicated and evolving, and most teachers aren't prepared to teach it well. Many textbooks don't touch the topic, according to science educators.

"Climate and earth sciences more generally have been historically neglected in American science education," said Glenn Branch, deputy director of the National Centre for Science Education, which tracks anti-science education legislation and develops curriculums like the one Ms Lau was teaching.

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"Lots of teachers feel they don't have the content knowledge or pedagogical know-how to teach climate change effectively."

And then there are the politics, especially in ruby-red Oklahoma. Educators here say they occasionally receive questions and pushback from parents when classes cover climate change.

A state agency funded by the oil and gas industry pumps money into teacher training and classroom materials, including books featuring a cartoon character called Petro Pete, with the goal of promoting fossil fuels. And state lawmakers routinely introduce bills that critics say would encourage teachers to spread misinformation on evolution and climate change.

"Every year, we have to fight one or two bills," Ms Lau said. But she added that even here in Oklahoma, there's a growing hunger for accurate information on climate change: "I don't get the resistance I got at the beginning of my career because it's getting harder and harder to deny."

Wearing a denim jacket with an "I teach climate change" button, Ms Lau showed her students a video that used a discussion of sports doping to explain the probability aspects of climate change. Steroids can make it easier for players to hit home runs, the video explained. But it's impossible to know if any single home run is due to doping.

So to assess the effects of the drugs, one has to observe a player's performance over time. Same with climate change: Some extreme weather events occur regardless of whether humans are pumping extra carbon into the atmosphere. Scientists can determine if these emissions are affecting the climate only by following patterns over time.

As they scooted out of the classroom on the first day of Ms Lau's two-day lesson, a few of the sixth-graders said this was the first they had heard of climate change.

Others said they knew a little about it. "The greenhouse gas gets trapped in our atmosphere and it's melting ice caps," explained Jewel Horn, who said she'd learned about the topic previously in science class. She said she didn't worry or talk about the topic much: "It's not that big of a problem unless we do nothing."

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In teaching about climate change, Ms Lau says she is fortunate to have support from her school's administration. She has also learned how to choose her words carefully, especially given that so many people in the state (including members of her family) earn a living from carbon-intensive industries such as farming and oil and gas.

"I tell my students, just because your parents are currently working for Devon or Chesapeake, what they are doing every day is not bad and evil," she said, mentioning two of the big Oklahoma-based energy companies. "It's just that overall, we need to start looking for other directions."

Teaching about climate change got a boost six years ago with the release of the Next Generation Science Standards, which instruct teachers to introduce students to climate change and its human causes beginning in middle school. To date, 20 states plus the District of Columbia have adopted the standards, and many other states have embraced a modified version.

All told, 37 states and the District recognise human-caused climate change in their science standards, says the National Centre for Science Education.

Oklahoma's standards are based on the Next Generation Science Standards, but while they discuss human effects on the environment, they do not directly attribute climate change to human activities. Even so, some state legislators called the language on climate science "one-sided."

And just because something is in the standards doesn't mean it's being taught universally, or effectively, especially given that textbooks take time to be updated.

"We're in a transition period right now," said David Evans, executive director of the National Science Teaching Association, which issued a position statement in September endorsing the teaching of climate change.

To teach climate change, educators are turning to a growing number of online materials that have emerged to fill the gaps. Professional development opportunities are popping up, too, although teachers often have to cover the costs to attend.

Last summer, Ms Lau spent 32 days in northern Alaska on a professional training for teachers. A native of rural western Oklahoma, she says a "series of small epiphanies" fuelled her commitment to learning and teaching about climate change.

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Standing before her sixth-graders on the second day of her lesson, she showed them data she had collected from the Alaska trip. There were measurements of melting permafrost, images of roads sinking as the frost under them thawed and photos of coastal villages that were having to pick up and move.

"They're moving the entire town," Ms Lau said. "In the United States, that's happening."

Jewel, the sixth-grader, said the second day of the lesson left her more worried about the Earth's warming. "Now that I know more about the facts of climate change, it's a little bit easier to believe," she said. "It feels like more of a threat."

Her classmate Dan Nguyen had a darker outlook. "Now, I'm thinking that we're in a crisis." It made him a little angry, he said, and he felt people "should be more careful of what they are doing, what they are using."

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His fears aside, there's something of a disconnect between the urgency of the scientific view of climate crisis and the relatively dispassionate manner in which Ms Lau must talk about it. Globally, children have been among those raising the alarm on climate change and calling for action, through a lawsuit and school walkouts.

But Ms Lau's students are still young, far from voting age, and she says she has to tread carefully, to find a way to teach the subject "compassionately but head-on."

"That's part of the challenge of teaching climate change - it's so multifaceted. We are learning so much every day," she said.

She added that she had to find a balance between "getting them to understand the severity of it but at the same time leaving them hopeful."

She said: "I don't want them to grow up without that hope."