A common question I get from parents is should my kid, who is an athlete, (usually the pre-teen years 10-12) start lifting weights?
The way I go about training kids this age is typical to a curriculum they'd receive at school.
I've developed an athlete fundamentals program that teaches:
1. Necessary movement skills (linear speed, lateral speed and change of direction and reaction), jumping skills (skipping, hopping, jumping),
2. Body weight strength training (planks, push ups, pull ups, squats, lunges, etc.)
3. Principles of warming up and preparing for training.
4. Slowly progressing to teaching the mechanics of conventional strength training exercises (hang cleans, squat, dead-lift, bench press, overhead press, etc.
As far as teaching strength training, I start them with soft resistance like medicine balls and even kettlebells for teaching squatting and dead lifting technique. The goal is always looking at the long-term development of the athlete and getting them prepared for their next training stage.
So for this age group it's developing a sound base of fundamentals of movement and teaching them the technique of lifts they will use throughout their athletic career. Repetitions will generally stay high as we are grooving movement patterns.
Attentiveness of coaches is of ultimate importance at this level of development. As we know, kids at this age can lose their concentration pretty fast, and sometimes just don't have the ability or coordination to maintain proper form throughout a set.
This is also one of the best times to reinforce some of the other areas young athletes will take with them throughout their career, like how to warm up, weight room etiquette, being on time and learning about how their body works.
Once they graduate from the fundamentals program, they will be ready to advance with ease to either their school's strength and conditioning program or the next level of my high school strength and conditioning program. This foundation helps them get the most out of those training years as well.
Your kid, at 10-12 years is old enough to be in a safe and sound athletic development program. Training should be based on teaching fundamentals, grooving movement patterns and preparing them for their athletic development journey.