Repetition is one of the primary keys to effective memorizing. Without repetition (3 is a key number) you cannot expect to remember anything. Repetition is how we first learned our alphabet back in preschool.
Reenactment is another tool. Every year we reenact wars and battles, not only to honor our fallen soldiers, but also to remember our history.
To be effective, reenactment must include thinking about the meaning and sequence of thoughts and words in the passage each time they are repeated. Without meditating on the meaning of the passage, repetition soon looses it value.
Follow a system
It is equally important to teach children HOW to memorize. If you tell a child to tie his shoe or clean her room and never show them how, they only get frustrated and quickly give up. Often times they won't try again.
1: Read silently over the passage to be memorized.
2: Starting with the first verse in the passage, "break off a chunk" of the verse so that it is small enough to easily be retained. This is often done at punctuation mark.
3: Read that small portion audibly from five ten times (can also be done under the breath). Think
about the words and the meaning of the portion being read.
4: Recite this small portion audibly five to ten times without reading it.
5: If it can be repeated from five to ten times without looking, leave that portion and move on to the next. If it cannot be done yet try again (other options listed at bottom)
6: After the second portion is learned, associate it with the first portion and say both together several times.
7: Learn one verse (may needs to be split into smaller chunks) at a time. As each verse is learned, say it together with the preceding verse in the passage
If you are a hands-on learner, try writing the portion on a chalk/white board. Erase a word or two at a time And continue to recite the verse until you can say it five to ten times with the entire board cleared.
If you have an active child, make up moves for every word/every other word (doesn't have to be proper sign language. What ever helps the child remember the word)