I count an effective lesson plan one in which:
1. the students learn and retain the information and/or skills
2. the students are involved with their learning
3. the students aren't bored and their attention focuses on the lessn
4. the students may even enjoy the class session
Of the above, number 1) is paramount, although I would have the word apply added.
Think of teaching a group of kids to use a bow/arrow to hit a target 30 feet away. That is the lesson objective, although most would add do it safely to the objective.
You teach them how to hold the bow, how to load it, how to keep it pointed downrange, how to aim, and how to release. Then you give them guided practice (each student needs differing amounts and levels of guidance) until most are hitting the target some of the time. You schedule another practice session at a later time or date (we learn by repetition spaced over time).
after a couple of practice sessions, you evaulate.
Notice how 2, 3, 4 of the above is integrated into achieving 1). That is a lesson.