lifting for 8th graders

This winter our program will be starting a lifting program for 8th graders who will be moving up to JV football next year. At our school JV is 9th and 10 grade. The program is more to get the kids into the habit of lifting and building unity through weight room work than it is building strength. Building strength is more like Goal #1a. There will be a lot of emphasis on proper form in performing the lifts and spotting. I will be the one working with the kids and the Varsity HC has given me control of this program and I'm looking for some advice. We are planning on two days a week. We will only get about 1/2 hour of lifting time due to after school bus times. Currently the plan is for a two day rotation with a chest/tri/shoulder day and legs/back/bi day. The main lift for each day is a flat bench for the chest day and squat for the legs. After that there is one exercise for each part for a total of 4 lifts. However, I am also considering making it a 4 day program with 4 separate main lifts and you only hit those main lifts once every other week while also cutting down the number of body parts and total lifts for the day. I hope that sounds coherent. There's a rough idea below. Let me know what you guys think.

2 Day Plan

Day 1
Main lift - Bench
chest lift
tricep lift
shoulder lift

Day 2
Main lift - Squat
leg ext or curl
back lift
bicep lift

4 Day Plan

Week 1
Day 1
Main lift - Bench
Chest lift
Shoulder lift

Day 2
Main Lift - Squat
Leg ext or curl
Back lift

Week 2
Day 3
Main lift - Hang Clean
Shoulder lift

Day 4
Main lift - Dead Lift
Walking lunges
Bicep Lift