Chapter III, Part 8 of the DMC takes a look at the parts of the Mass. In fact, these sections and the fifteen that follow will detail some specifics on various Mass parts and how they could and should be prayed with children.
First, a reiteration of what we all know:
38. The general structure of the Mass, which “is made up as it were of the liturgy of the word and the liturgy of the eucharist,” should always be maintained, as should certain rites to open and conclude the celebration. [GIRM 8.] Within individual parts of the celebration, the adaptations that follow seem necessary if children are truly to experience, in their own way and according to the psychological patterns of childhood, “the mystery of faith . . . by means of rites and prayers.” [Sacrosanctum Concilium 48]
And a caution that Masses with children should not be significantly different from Masses with adults:
39. Some rites and texts should never be adapted for children lest the difference between Masses with children and the Masses with adults becomes too pronounced. [See DMC 21] these are “the acclamations and the responses to the priest’s greeting,” [GIRM 15.] the Lord’s Prayer, and the Trinitarian formulary at the end of the blessing with which the priest concludes the Mass. It is urged, moreover, that children should become accustomed to the Nicene Creed little by little, the right to use the Apostles’ Creed indicated in no. 49 remaining intact.
Calling out the Creed seems out of place. Only on holy days, do school Masses use the Creed at all. Unless the CDWDS was suggesting children’s Masses, or at least adaptations for children present on weekends.
My sense is that the Nicene Creed is fine for children, and probably better to teach to them from the start. My own story (though granted I was eleven at the time) was that by my own baptism, I knew the Nicene Creed from Sunday Mass attendance. The Apostles’ Creed was tougher because I used it less frequently. I was told that I would need to recite the Apostles’ Creed at my baptism liturgy. So I memorized it, hoping I would not accidentally slip into the longer version.
As my family and I entered the baptistery, what do you think I beheld in the stained glass window behind the priest? The Apostles’ Creed.
In my youthful mind, I declined the assistance–it was important to know and demonstrate I knew the profession of faith. When it came time for me to recite the Creed, I kept my eyes on the baptismal water and didn’t use the crib notes above me.