i think teachers and the school administration should take it into consideration and teach children by doing loads of activities with them.
As others have said, your definition of "activities" greatly impacts this question. Also important are factors like the subject being considered, the age and ability level of the students involved, the preferred learning styles of the students and the preferred teaching style of the instructor, the availability of time and space and materials, etc...
All activities need to be developed based on how they will help to further the learning process for the students. This opens a wide variety of possibilities from which teachers may draw, depending on their needs and goals for a particular class at a particular point in the learning process and the particular needs of the students.
I agree that a good learning environment involves both activities and lecture. What I am concerned with is the fact that you seem to separate the two (activities apart from education). Activities should be grounded in the lesson. Keep in mind, teachers are not there to entertain you--they are there to educate you.
I think cooperative learning activities are incredibly helpful and, when done correctly, lead to more learning than when teachers stand up and lecture. However, these activities should be connected to an assignment of some sort so that teachers will know whether the student learned the objective of the learning activity. Assignments also help students themselves to know if they are on the right track. If you have an assignment returned with comments or suggestions, you know that you weren't going in the right direction with the activity.
Especially in the upper grades, all activities should have a learning goal. Teachers who have students complete activities for pure "fun" are wasting the instructional time they have. I have never understood the instructional value of a word search, but I have seen many come home with my younger son and I even see them on the copier here at the high school where I teach. Students may like them for the "fun" for it, but that is time they will never get back.
Hopefully, all school activities--be they testing, lecturing, group-oriented, sports, etc.--will be focused on the student "learning" from the style of lessons presented. Many students seem to forget that the school hours are intended for educational focus, not social interaction. A well-rounded lesson plan will present students with "fun" assignments, but non-learning activities in school could be considered a waste of time--and in this economic climate, a waste of tax-payers' dollars.
Just keep in mind that there is never going to be any academic class that will be interesting and exciting to all students. It's not possible for any teacher to do only activities that seem fun to the students. Some of the time, students have to realize that education is something they need, not something that is purely entertaining.
I'm not sure what you mean by "activities," but in general anything that gets students and teachers interacting in learning processes seems valuable to me. In other words, merely lecturing strikes me as less important than getting students to ask questions, actively think, and become active learners rather than remain passive audiences.
I agree with the idea that teaching involves many different ways of helping students learn. I have found however, that as I mentored student teachers, they were creating activities without really understanding the purpose or how the activity was supposed to help the students learn. Purposeful activites, well planned and with a goal in mind to help students with a difficult concept or reinforcement of previous learning, are what is needed. As post 2 indicated, a variety of creative teaching methods are necessary because we know that students have many different learning styles, and one method alone is not enough.
I think any successful teaching is going to involve a series of different activities. This will involve some traditional teaching, but should also involve some different, more novel and creative teaching methods. This is what is necessary to help learners to learn.