Volleyball Serving

Though you're absolutely correct about the push-ups, be careful with your admonishment, especially since you're new. Kids this age can be highly sensitive.

Again, always think evaluation points when you're teaching a skill, and then follow up relentlessly.

I might, with that amount of students, consider consolidating that game to one net. That leaves you space to perhaps bring some students who need work, to an empty net.

2nd Day of Overhead Pass

Since track is one of your strengths, feel free to inject your knowledge into the warm-ups. PE teachers often give students things to do with no follow-up. I follow the notion that there is always teaching to be done, particularly with the dynamic warm-up.

One of the biggest issues with volleyball skills has nothing to do with the arms. Students try to reach too much, rather than getting under the ball.

2nd Day of teaching, volleyball 1st period.

Yesterday, I hope you saw two things over the course of the day. One, most classes have a unique personality, which is exacerbated even more with the different lab days. Second, how you teach a lesson at the end of the day may be markedly different than the beginning of the day.
Normally, we hit towards the dividers, to avoid an aerial assault on the middle of the floor. I like that you changed that, with the presence of the net, for court awareness reasons.
Good correction to remind the students to continue to drill with two hands and not one.
Some of the breakdowns in skills can be helped by merely having the students move closer.
It is a good idea to have the students catch a bad ball, when drilling, so they don't emphasize bad habits when hitting.  There is a time to practice bad ball hitting, I don't know if it's 9 grade PE.
As you get to know the kids, you can use a mature, skilled student to sometimes assist special needs students,  They may even relish the role.

Volleyball 1st Day

Great idea to draw on your military training for a warm-up.

Good circulation around the perimeter of the room, try and move to the interior, as well.

Voice projection for the warm-up is good, still needs to improve overall when activity is stopped.

Have the students hold the balls still while you are talking.  They'll always want to bounce or pretend they're "Globetrotters," with a ball in their hands.

If you have the whole gym, use it.   Most of the kids were on one side of the gym.

Specific feedback to volleyball drills

Students will set/bump and catch for a surprisingly long amount of time.  Your inclusion of three drills was good.

Since the nets were up, utilize them for students having an awareness of height and distance needs for their passes.

Simple feedback for contact is having little or no rotation on the ball for setting.  Also utilize sounds for feedback, make a big deal if you like the sound of a set or bump pass.

Some common volleyball mistakes were evident.

1.  Unless they are very seasoned or athletic, keep the kids on the ground, usually for setting, always for bumping.
2. Students often extend their arms too soon. I point out to them that this leaves merely the wrists for power.
3. Some also do not extend.  Have them freeze at the end of their skill and have them adjust.