Why can't they think for themselves? 
I've told them a thousand times, but they can't remember how to play that phrase the next time we meet! 
Every time they improvise they play the same old thing. 
What can I do??!!

Encouraging children to think for themselves and to think in creative ways is a skill that must be developed.  Just like singing in tune, learning to read eighth and quarter note rhythms, learning to breathe correctly, and a host of other musical skills, children's creative skills  (i.e., divergent musical thinking) develops slowly.  The creative process must be part of the children's daily musical program.  Children can learn to think musically.  And with some guidance they will thrive, musically.

This page offers some suggestions on how to help your students think "out-of -the-box."  Many of the ideas were influenced by Jackie Wiggins text Teaching for Musical Understanding (2000), MacGraw Hill.  I encourage the reader to read Wiggins' text.  It is a wonderful resource, packed "chock-full" of classroom tested lesson strategies.

The most important thing to remember is that all ideas are welcome in the music room.  Often, in a effort to bring children to the best sounding musical experience we can provide, we cut corners.  Most likely, the corners we cut happen to be musical ideas offered by our students--ideas that may not "fit" our idea of how the music should sound.

There is no "one right way" to make music.
Related to the first point, is the idea that we don't have much time with our students, so to save time we give them the "right" musical answer.  When we tell students how they should create music, we impose our musical knowledge.  Possibly, we send the wrong message: My musical ideas and knowledge are superior to yours.  Always seek help when making music.

Give your students the freedom to make musical mistakes.
At the elementary level, the process is more important than the product.  Children will have a lifetime to work on musical perfection.  Musical ideas that don't work are beneficial in the long run because through trial and error, children will learn which musical ideas tend to work and which don't.

Encourage small group projects.
The educational literature seems to suggest that small group work and peer interactions benefit children's learning.  Children can learn from each other, use this to your advantage.