A steady stream of backpack-toting teenagers flowed into Almonte Food Market, a bodega on the corner of Emerald and Sergeant Streets in Kensington, beginning around 7:30 the other morning. They were stopping to buy food before the first bell at Kensington Health and Sciences Academy, a public high school just down the street.

I wanted to see what they were eating.

The most popular purchase: Flamin’ Hot Cheetos.

A few students were buying the $3 bacon-egg-and-cheese breakfast sandwich on a roll, or the $1.25 pastelillo (a meaty Spanish pastry), or the three-for-$1 meat sticks that resemble Slim Jims. But most purchases were from the American junk food panoply: Doritos, Chips Ahoy, Oreos, Tastykakes, Pringles, Cheetos, SunChips, powdered donuts, vanilla-cream sandwich cookies.

And then to drink, assorted sugar-laden iced teas and fruit punches and juices.

While schoolchildren have been enjoying packaged snacks for more than 50 years — I am pointing a finger at my childhood self — what was startling to observe on this morning was the number each student bought. Not one or two items, but four, five, or six — for breakfast, for snacking throughout the day, for lunch.

I asked if the snacks would fill them up, if they wouldn’t be hungry an hour later. “It holds you,” one young man said with a shrug.

A young woman had her purchases lined up on the counter: Tastykake Coconut Junior Cake, Tastykake Sugar Wafers, BBQ Pringles, and Arizona Iced Tea with lemonade. “The school lunch is not good,” she said. “So I buy this.”

Many students were spending $3 to $5 on snacks, enough to have purchased a breakfast sandwich and fruit. Although there were oranges, apples, and bananas for sale, I did not observe a single purchase of fruit. However, the fruits available were vastly outnumbered by the dozens of packaged snacks.

According to a 2009 study published in Pediatrics, the average Philadelphia student bought more than 350 calories on each visit to the corner store, with almost half of them shopping twice a day, five days a week.

I certainly didn’t observe any improvement to that statistic. By my calculation, many total purchases on this recent morning topped 1,000 calories, mostly via snacks low in nutrients, loaded with fat and sugar and salt. The Tastykake Coconut Junior alone was 370 calories, with 19 grams of fat, 34 grams of sugar, 230 grams of sodium, just 3 grams of protein, and 1 gram of dietary fiber. Not the stuff that a brain and body need to perform well in the classroom.

Packaged snacks are increasingly replacing meals, in part because of their convenience and low cost, according to the NPD Group, which does food market research. And with so many snacks designed to be addictive, it is no wonder that more are being consumed at once.

With the national obesity rate for children between the ages of 5 and 18 hovering around 15 percent, and in Philadelphia at 20 percent for the same age group, many efforts are underway to combat the trend. Philadelphia is at the forefront with initiatives like the tax on sugary drinks, nutrition education in schools, and the Food Trust’s Healthy Corner Store Initiative, which increases fresh foods in bodegas.

As the recent visit to the local bodega shows, it is a tough trend to reverse. But that is the mission behind the after-school cooking program, My Daughter’s Kitchen: teaching children how to cook healthy, affordable meals for themselves. Inspired by lessons I taught my own daughter, the program is now in its sixth year, and this summer became its own nonprofit organization. More than 40 volunteers are teaching classes in 21 schools in Philadelphia, Camden, and Chester.

After my visit to the local bodega, I headed to one of those classes at KHSA. Mini frittatas were on the menu, with a lesson focused on the importance of a nutritious breakfast.

Sarah Goldman, a young algebra teacher who loves to cook, was leading the class and doing her best to sell the idea of a healthy breakfast. In her late-morning classes, she often notices students getting hungry and irritable, making it harder for them to settle down.

One student, Gabriella Miller, 17, made it clear that she would not be making mini frittatas at home for breakfast. “That is just not realistic,” said Gabby, who had chips and trail mix for breakfast that morning.

Her teacher was undeterred. “You could make them on a Sunday night and then have them all week,” her teacher suggested. Gabby gave her a look that said, “Really?”

But the enthusiastic teacher pressed on. She demonstrated how to properly chop the onion: Grip the knife at the top of the blade so it’s sturdy in your hand, she said. Keep the tip down, cut the onion in half, then cut horizontal lines.

“What slope would a horizontal line have,” she quizzed, throwing in a little math.

“Wouldn’t it be zero?” said Cheyene Perez, 15, another student.

“Yes!” said Goldman.

As the students worked through the recipe, Goldman passed along lessons from her grandmother who taught her to cook: The onions are done when they are clear; always crack the egg on a flat surface, not on an edge; and never, never buy olive oil in a plastic bottle. It will taste like plastic, her grandmother told her.

When the spinach and onions were cooked, then evenly distributed in the muffin tins, the egg mixture was poured into the wells and the tin was placed in the oven. The students cleaned up and set the table.

What would make it easier for them to cook for themselves, they were asked while they waited for the frittatas to bake. What would motivate them to cook at home?

“If it’s quick and I could make it myself, and if it looked good to eat,” said Cheyene.

“Hunger,” said Gabby. “And if I had all the ingredients and the energy to make it.”

The frittatas puffed up in the muffin tins, browned beautifully, and smelled enticing. And they tasted good enough that even the reluctant Gabby gave a thumbs-up.

“I thought it was going to have no flavor. But it was much better than I thought,” she said. And then, giving her teacher her due, added: “I could even see making them the night before so I could have them in the morning.”

Contact Maureen Fitzgerald at mydaughterskitchen.com. Read about other classes at inquirer.com/mydaughterskitchen.