Ask 8-year-olds in most parts of the country to name invasive species in their town, and you’d get a lot of confused looks. But when Matt Steffy, a natural resources specialist at Homer Soil and Water Conservation District, posed that challenge to a class of third- through sixth-graders at Fireweed Academy on Nov. 20, the response was immediate.

“There is mint is all over our garden but we never planted it, it just came up, ” shouted out one eager fourth-grader.

The students raised their hands to shoot off the names of species, rapid-fire: hawkweed, canarygrass, oxeye daisy. Whether they’d had to avoid stepping on hempnettle in their yards or helped their parents burn Japanese knotweed, most of the kids present were already veterans of a war with presumptuous plants.

Thus, this presentation was an important one. The talk was a primer on invasive species — any species that comes into an environment where it isn’t native and spreads enough to compete with native species and damage the ecosystem — and a discussion of how to deal with them.

After coming up with a list of invasive plants in Homer, Steffy and the students talked about how the species got here and how they affect a habitat. He explained that non-native species come in with visitors, human and non-human, and spread in lots of ways, like on machinery or with food or on the wind. And when a species without natural predators comes into an ecosystem, it can really mess things up — like when rats from Norway invaded the Aleutians and started eating all the bird eggs.

Among the clarifying points Steffy made over the hour-long presentation was that animals, not just plants, can be invasive species. Another was that just because something is a pest, like a mosquito, doesn’t mean it’s invasive.

He also pointed out that “invasive” is a relative term specific to a place.

“Something that’s native to us and a very big part of the habitat, once you put it somewhere else can become an invasive species,” he said. The fireweed that makes fall so beautiful in Alaska is taking over native plants in China and costing the country’s government big bucks to eradicate, he explained.

Steffy didn’t shy away from big words, and the kids kept up. Students learned about allelopathy, a competitive mechanism plants use to poison other species around them; seed viability; and manual, chemical, cultural and biological ways to fight invasive plants, from hosing off machinery and pulling up unwanted species to injecting herbicide into roots — something he can do as a certified pesticide applicator.

Occasionally fidgety but always attentive, the students had lots of questions. What’s at the top of the invasive species list to deal with in Alaska? What species in the bay are invasive? Are they why so many otters are dying?

Steffy answered as many queries as he could and left the class with contact information for his office, telling kids to stop by anytime. He also handed out pocket field guides to common invasive plants in Homer, information sheets to color in and a pile of stickers.

Students should keep an eye out for invasive species and learn how to keep them from spreading, he said: “We can all be scientists and we can all have our ears on the ground.”

This was Steffy’s first school presentation of the year — his daughter is a member of the class — but he said he’s hoping to visit others. He just needs an invitation.

“I love it. Every year I try and seize every opportunity to go to every classroom,” he said. He’s also worked with Fireweed students at the schoolyard habitat behind the building, where they can learn about local ecology and get their hands dirty at the same time.

After the presentation, students headed to lunch. A few stuck around to ask more questions.

“I thought it was pretty cool how so many kids had stories to connect to it,” said fourth-grader Poppy Smith.

Teaching aide Meldonna Cody agreed. “I was really impressed with how knowledgeable the kids were. I thought their questions were on a pretty high level,” she said.