I work with 180 new 6 thru 8 year old batters every year for over 25 years and there is one thing I have learned NEVER hold back a fully technical synchronized swing because you think these kids can’t handle the motor skill, they actually can learn a proper swing easier than established swing older kids. This is when to get it right!
“I am struggling to find a way to teach hitting mechanics in a way that makes sense to 8 year olds.”
No worries if you make it fun for them with caring exuberance and they will all respond well. You should teach them in succession the 4 parts to the swing, stance, timing mechanism, pivot then upper half swing and finish. Early rotation is not a problem with this age group! The problem comes from not using the forearm and hands correctly. This is why I use the batters press along with the most important first soft toss drill, I take a broken (at the bottom) tee and place it behind and inside a little with it raised to hip high, this makes them understand (proprioceptively) that with the initial shoulder forward movement that they are not allowed backside drop, when I toss the kids I stop the ball to see if they gather and stride correctly then flip it and work on the rest. When they learn this timing mechanism I will then throw with out a stop but will stop occasionally to back check retention of the stride and gather. Next do the one arm drill 3 swings backside 4 swings front side 3 rounds. I then have them do a rapid-fire session to help them learn how to stay closed off and build rhythm. Front side bowling toss is great for building an uninhibited swing for these guys. Then do a little live you should let them pull all they want until they are 10.
“I need to talk to his mom and tell her to not go back there.”
This is not behoove you to do this, remember all swings work, they just create different exit spins. Why don’t you just go out of your way and talk to the instructor?
“the first left turn circuit”