There are several middle school teachers and high school teachers working with me.
Some of them have created simulation with ejs and some of them have created animation with flash.
Their work can be found either at my Chinese forum or [url=http://enjoy.phy.ntnu.edu.tw]Science Garden[/url] web site (Both of them are in Chinese).
One of my MS students have created EJS simulations for assessment purpose. We have compared similar type of physics concepts assessed with traditional way (text sentences and images) and ejs generated simulations.
We only found gender difference , however, it might sue to computer skills between boy and girls.
Another MS students have created simulations to help students understand wave phenomena.

I have tried to teach first year undergraduate students using EJS to create simulation in the past 4 years. However, most of them did not use it after the class is over. May be they are too busy or may be I have pushed them too much.

I was not able to find teachers who is willing to use EJS as a learning tools for high school students yet.
It will be great if you can find teacher who is willing to try it for high school students.

I would suggest the following steps:
1. create simulation similar to physics problem in the text book and let student play with it to solve the problem.
2. create standard physics simulation for students to modify some of the model.
for example: create a projectile motion with any drag force and ask students to add any type of drag force (proportional to velocity or velocity square) and compare with original result.
3. Let the student starts to create simple model simulation.

It might take a long time from step2 to step3. Let the students familiar with the EJS environment first and let them know EJS can help them (instead of adding their load -- this might not be easy).
Many of my students think that EJS is too hard for them. But some of the students do enjoy it and some of them have created good simulations as their final project outcome.

Instead of asking each student to create his own simulation with ejs, for high school students, may be it is better to ask each group to create one or two simulation at the end of the program.

I will be willing to help as much as I can. :-)