"Why isn't the electricity flowing?" she asked a group gathered around a desk as they built a version of the popular children's board game "Operation."
"We need a conductor!" some kids said loudly.
"Why do you have to tape two parts together?" the teacher prodded.
"Because it wouldn't be a complete circuit," students responded.
As they figured out how electrical energy can be transformed into light and sound and applied the principles to make a red light flash and activate a loud buzzer on their games, the 9- and 10-year-olds formed their own questions.
"Why isn't mine working?" wondered Armando Ontiveros. "I'm stuck."
Poulsen called on fellow classmate Gavin Livingston to help Armando.
"Can you help him figure out why?"
Gavin looked at Armando's project involving the ageless, utilitarian shoebox, batteries, holes and wires.
"You have to make sure all the wires are connecting right and aren't out of order. I'm having a tough time myself,"
Gavin said. "I've learned that you don't always get stuff on the first time. You have to keep trying."
That was one of the many valuable lessons students took home last week, as they worked on a special science project that enabled Poulsen to try out new teaching techniques.
"I spent a lot of time questioning my students today," she said, "and I think I frustrated them because they're not used to being asked questions. But it pushes them to succeed."
Poulsen is one of 29 K-12 teachers across the state to become students again, in the quest to find the best ways to teach the all-important 21st century STEM - science, technology, engineering and math.
She's a participant in the Colorado Champions for STEM Education Leadership Academy, or COSTEM, offered by Biological Sciences Curriculum Study.
The Colorado Springs-based nonprofit known primarily by its acronym, BSCS, develops science curriculum, conducts research and provides professional development to educators.
The two-year COSTEM program started last summer and already is realizing benefits in the classroom.
"It pushes me to be a better teacher and think about things in a different way, outside the box," Poulsen said. "I've had good success with it."
Coaxing students to identify the reason for a problem - or the "why" - and then interpret what that means is one of the COSTEM strategies Poulsen is using. It's an advanced teaching method for elementary school students, she said, one that encourages them to think for themselves as they search for solutions.
In addition to being inquiry-based, COSTEM follows current academic standards so it's relevant and easily applicable, Poulsen said.
A grant from the Gay and Lesbian Fund for Colorado pays for most of the program's cost, excluding a registration fee, said Brooke Bourdelat-Parks, a science educator for BSCS and director of COSTEM.
The program includes a week-long summer institute and four additional sessions over the course of a year. Teachers, school administrators and "community partners," such as Challenge Learning Center of Colorado, form teams. After learning effective teaching practices and assessment strategies for STEM subjects, participants share the information within their school districts.
The first cohort, which has participants from Colorado Springs and Grand Junction, will have its fourth training session on April 26. Through March, BSCS is accepting applications for new participants from around the state. The new group will start this summer.
STEM education is important because it helps prepare students for today's workforce, Bourdelat-Parks said.
"The critical thinking and analysis skills of STEM are what they will need not only in a job but also to be a literate citizen who, for example, knows how to analyze what people are saying and vote," she said.
BSCS studies how students learn and then creates programs for teachers, she said.
What they know: Students need to organize their ideas into a framework, and then reflect on what they've learned.
Teachers are encouraged to take that approach and get to practice during the academy. Participants in last summer's institute investigated how to clean up an oil spill using vegetable oil, a shoe box and an extraction tool.
To discover the most efficient method, they performed a computer simulation. They analyzed and interpreted the data, wrote an explanation of what they saw and gave a presentation about what they learned.
The experiment could easily be applied in middle school classes, Bourdelat-Parks said.
The best part, Poulsen said, is that students are benefiting from the new direction in teaching.
"A lot of elementary school teachers don't teach science regularly, or it's like a craft or an after thought. Incorporating STEM principles is not more work, it's working smarter," she said.
Latiana Childress, one of Poulsen's fourth graders, said she loved the Operation game project.
"It's really fun. It's hard sometimes, but that's what I like about it - it's a challenge," she said.
"You have to get everything correct or else it won't work," said student Fabin Pelayo. "It's harder than it looks."