Keeping Players engaged During Practice

How is your practice divided? We typically go Individual, one special team, Group, another special team, and team. That's overly generalized of course, but it keeps kids in smaller groups, therefore getting more reps. Teach the new play in Indy, reinforce it in Group, and by Team, you can have a little more assurance that it'll come out mostly right. Also try to make subs sporadically instead of wholesale.

You should spend fifteen minutes in the classroom installing and then have both groups actually walking through at practice. What you are describing is not a walk through. The kids should be doing the work and making adjustments during a walk through.

What you are describing is instruction time.

Kids want to play that is why they signed up. If you need to teach do it in the classroom. During practice the kids should be practicing.

Keep them engaged by giving them something productive to do besides stand around and watch others get reps.

Instead of second team standing there, rotate them out every other play--call the play for them while first team is lining up to run it, then have them watch. If you have to call them out for not paying attention a few times, they'll eventually get the hint.

You can rotate scout team out in the same way if you have enough numbers, or break the 3rd team off with the JV or whatever to work something on the opposite end of the field.

Switch your 2nd team O in every 5 reps. I'd say 6 reps max, you could go lower if you wanted of course. If you do Scout Defence, do the same thing and switch your 2nd stringers in that are paying attention, that way the kids that are messing around on the sideline will realize the kids that pay attention and work hard in practice are getting reps even if they're not the best, while they (kids messing around.) are getting very limited reps.

Film practice and keep it moving. The teaching aspect is during individual time and the use of Hudl. When we get home from practice corrections are made during group and team time via Hudl. Practice fast, play fast. All of our attention spans are shorter than ever before.

We NEVER stop team to instruct because of this.

We want to get as many reps in as possible.

Only "instruction" are short coaching points from the OC (me), or personnel switches by who ever is running the scout defense

This stuff is all great, but you have to be careful to teach the drills and teach the skills first, which takes longer.  Otherwise you're just going to see a bunch of garbage reps that don't accomplish much.

When you're just jumping in like that, you see a finished product, but you miss all the work that had to be done up front to get to that point.  People used to rave about Chip Kelly's practices and everyone wanted to be up tempo in practice, coach on the run, etc. but without seeing how the Oregon staff:

A.)  Was recruiting players who were already pretty good before they came to him, so they didn't need to learn most of the fundamentals

B.)  Spent a lot of time in the offseason teaching these drills on a whiteboard, in walkthrough, etc.

A lot of them, myself included, found that up tempo practices with maximum reps and "coaching on the run" isn't always the best approach, especially for young and inexperienced/raw players.  In HS, if you don't invest in slowly teaching each fundamental and each drill in spring and summer, and even in slowing things down some once the season starts when you see things aren't being done right, then all the up tempo reps in the world aren't going to make you better.

We started having "stand by" drills set up and ready to go for groups that were not engaged. If we have a period with more than a handful of kids on the sideline, then we have a coach assigned to run the extras through these drills.... agility bags, cones, tackling bags, etc. It helped us in a couple ways....

1) less standing
2) any down time was being used to help kids get better at some aspect of being a football player (agility, tackling, blocks, etc)
3) more kids on the sideline wanted to sub in and play on scout teams. Regular rotations keeping the scout team fresh and giving the older guys a better look
4) more kids wanting to be on the field and get coached

I think there is a material difference between constant action up tempo as you seem to imply, and players being engaged in action (performing movement) as I imply . Now let me preface that I agree with your general premise, personally I have often been criticized for going to SLOW in my progressions in spring time, but I strongly believe in the following:" If you don't have time to do it right, when will you have time to do it again."

That being written, the practice policies I am writing about does not mean you gloss over fundamentals for the sake of constantly moving; if anything it means you go more in depth with the fundamentals. My players will be taught step 1, then perform step 1, and then repeat step 1 over and over and over until they can't get it wrong. We ask that the players 'DO' not just stand around and watch, but that does not mean we are just rushing through things for the sake of up tempo- it is quite the opposite.

Now, contrast this with a practice policy where a coach demonstrates something, then 1 player does it while everyone else watches. The coach then tells the first player what he did wrong and he goes back in line for the next player up. All the while the 8th player in line is sitting and not performing the actions. Or similarly where the #1s are out running plays for 10 minutes while the #2s stand in a straight line behind them getting 'mental reps'. I'll go to bat with the style that increase player performing the action they will do in the game.

We are what we repeatedly DO so having a practice where players DO those things (whole or part) they will do in the game more often is better.