Is it just me, or is eight years of age slightly young to grasp the intent and purpose of the scapular?
Well, yes and no.
There was an old-school traditionalist practice of investing all First Communicants in the Brown Scapular prior to Vatican II. (I received my First Communion in the 70s and this practice was long gone by then…we were lucky if our catechists ever mentioned a Rosary, scapular or religious medal much less invested us in one.) This practice has been criticized on some of the official Carmelite pages as having invested large numbers of people who were too young to understand what the devotion was all about and didn’t really practice it going forward.
They usually also understood it in terms of the so-called “Sabbatine Privilege” which, as porthos noted, is no longer accepted by Rome nor promulgated by the Carmelites. The official catechesis posted at the “Meditations from Carmel” site discusses this. (The Sisters of Carmel site should be ignred as it’s a schismatic group’s site and contains a lot of misinformation that we’re constantly having to correct on here.) Bottom line is that the kids should not be seeing the Scapular as a superstitious device to avoid Hell or to get out of Purgatory in 7 days.
And children usually don’t totally understand devotions, nor are they ready to commit to Carmelite spirituality for their whole lives - they may decide when they grow up they prefer Dominican spirituality, or Jesuit spirituality, or their own version of spirituality. Children usually want to do these things because their teacher is encouraging it, all their friends are doing it, they’re excited about being part of the group getting a new item.
Having said that, I think it’s good for a child to try out some devotional practices if the child wants to do it. I learned to pray Rosary with my parents around 7 or 8 years old, I wore a Miraculous Medal and like I said I attempted to wear a Scapular. By the time I was about 11 I had a “4 way medal” that I’d received from a sister who taught at school and I faithfully wore that for a few years.
Now I wasn’t perfect in any of these activities - the medals and scapulars would break, or when I got older they would show under my clothes and from a fashion standpoint as a shallow 13-year-old I didn’t like that. Nor did I say all the required prayers because in those days with no Internet and very limited info, neither me nor my mother really knew you were supposed to be “invested” in the Scapular or what prayers we might say besides a Rosary. But I do think Mary helps and gives graces to people who try even a little bit, and also, as an adult thinking of reverting, I had nostalgia for all those old medals and devotions I did as a child. It may be that these children, when they get older and slip off the path or consider taking a step off, will remember their childhood devotions and it will help them be pulled back.