Place a sheet pan in the oven and preheat the oven to 400°F.
Juice one of the lemons and combine with 3 tablespoons olive oil, the garlic, oregano, 1½ teaspoons salt, and ¾ teaspoon pepper. Pour into a bowl or resealable food storage bag. Add the chicken and toss or stir to coat. Let sit at room temperature for 15 minutes while the oven preheats.
Carefully remove the pan from the oven and place the tenders on one side of the pan. Put the broccoli on the other side, drizzle with 2 tablespoons oil and season with 1 teaspoon salt and ½ teaspoon pepper. Toss to coat. Bake for 15-17 minutes or until the chicken is cooked through and the broccoli is starting to brown.
Cut the remaining lemons into wedges and serve with the chicken and broccoli