As stated in the first part, Islam brought about reforms in the customs previous nations, including Arabs, had in practicing polygamy in Islam:

The Limitation in the Polygamy in Islam

The first reform Islam enforced was the restriction it imposed upon polygamy. Before the advent of Islam, there was no limit to the number of wives. One man could keep hundreds of wives and thus establish a harem for them, just as the ones some kings had, which is strictly banned in the religion of Islam.

However, Islam put a maximum limit on their number, and an individual was not allowed to have more than four wives simultaneously.

Justice:

The other reform that was made upon polygamy in Islam was the condition under which there must never be, for any reason, discrimination between the wives or their children. The Holy Quran explicitly commands:

"But if you fear that you may not treat them fairly, then [marry only] one" (4:3)

As a matter of fact, those men who can observe full justice with a number of wives are very few. It is clearly stated in the following verse of the Quran which is in association with the previous verse:

"you will not be able to be fair between wives, even if you are eager to do so..." (4:129)

Allah explains here that justice between the wives in its true sense - to stand exactly in the middle of the extremes - is beyond human power even if one may wish it. What a man is obliged to do is that he should not be totally inclined to one of them, leaving the other one as she were in suspense… [1].

Other conditions for Polygamy in Islam

Besides these two main restrictions, there are other responsibilities and duties polygamous men have to fulfill toward all their wives; such as Nafaqah (alimony) and Mahrieh (marriage portion), etc. [see the article about the rights of the wife over her husband]

The Best Form of Marriage in Islam

Ultimately, there is no dispute about the fact that monogamy is better; it is actually the best and most natural form of marriage in Islam. Obviously, the spirit of marital life which is oneness and unity is attained better and with more perfection with a single spouse.

It is only within this form of marriage that family commitment makes sense, and the great bond that unites the hearts of husband and wife makes them become one soul and one flesh [2].

Polygamy in Islam, on the other hand, rises from a social problem that rests heavily on the shoulders of all men and married women and for which a better solution has not yet been found. We have to face the fact that monogamy is not practical in specific social circumstances, and polygamy -under the mentioned conditions- is the most significant saving factor for monogamy.

A Choice between Conflicting Alternatives

One of two alternatives should be chosen: either the restricted acceptance of polygamy -as a duty rather than pleasure-, or the love affairs system, which is common in some societies these days. In other words, a few married men should marry more than one wife -of course under the condition of fulfilling all the above-mentioned responsibilities of a husband in a polygamous family-, and these will certainly not exceed a few percents, and unmarried women should settle, get home and make a life for themselves; or else open the way for love affairs.

In the case of the second alternative, the women deprived of family life may associate at her own free will with several men, and, as a result, almost all married men will in practice be polygamists.

Even then the matter will not end. The wives who will find their husbands to be unfaithful will think of taking revenge upon them and thus will themselves become unfaithful. This final result has been summarized in the well-known Kinsey report in one sentence: “The men and women of America have surpassed all other nations in unfaithfulness” [3].

Now, which alternative do you think is better?

References:

1. polygamy
2. Morteza Motahari, women and her rights in Islam, p. 148
3. Morteza Motahari, women and her rights in Islam, p. 150
4. polygamy in islam

A significant part of children's rights in Islam address the needs and demands of children during their years of adolescence.

Instruction for Middle Childhood (8 to 14 years old)

Middle childhood is the most decisive period of life, considering children's rights in Islam. It is a time when children develop fundamental skills for building healthy social relationships and learn roles that will make them ready to be confronted with adolescence and adulthood.

According to Islam, in this period a child should first be given necessary religious education so that he/she may not be misinformed and misled by anyone in belief or action.

In this stage, children should start to learn writing and reading. Also, moral characteristics and attributes should be institutionalized in their mind, and their acts step by step.   

Imam Baqir (AS) has asserted: “When the child completes seven years, he should be asked to wash his face and hands, and then told to pray. This will continue till he reaches the age of 9 years, when he should be taught proper Wudu (Ablution), and should be guided by parents if he is not careful and proper Salat (prayer) - and he should be reminded if he is not regular” [1].

It is worth mentioning that puberty in most girls will begin at around 8-14 years. If a girl has reached puberty in this period, she must do all acts of worship that an adult is required to do. Parents should have particular attention to the girls in this age. So she must fast in Ramadan, and she must also cover her head when she prays and thus must be in full Islamic prayer clothing.

Prophet Muhammad (PBUH&HP) emphasized the teachings of two things to male children, as a part of children's rights in Islam. He said: “It is the right of the male child on his father to teach him the Book of God (Holy Quran), riding, and swimming.”[2]. It is also narrated that the prophet believed the duty of a father to be teaching his son to write [3].

The character of children is supple; they may easily be bent in any direction. If they are not given proper moral and religious education at this stage, changes of manner and thought would be difficult.

Children's Rights in Islam During Adolescence (after 14 years old)

This period is between childhood and adult age. After the age of 14, the human mind becomes stronger and new horizons are opened in front of one’s eyes. Therefore, puberty, marriage, domestic life and its complex problems come to the fore.

Nowadays, the young adults soon realize that he needs to look after himself in future; he knows that with every day passing, he becomes closer to the responsibilities and accountability of a family.

It is the right of adolescent to be involved in every decision making in family and parents should consider their opinions. As Prophet Muhammad (PBUH&HP) mentioned the child is the master for seven years and a slave for seven years and a vizier for seven years [4].

One of the children's rights in Islam that parents should observe is to be provided with marriage when they are old enough, without delaying it. Indeed, the Holy Quran and the Prophet (PBUH&HP) advise that young people be married when they are old enough [5].

The prophet (PBUH&HP) said: “Among the rights of the child over the parents are three: To give him a good name, to teach him to write and to help him marry when he comes of pubescence [6].

The aim of Islam regarding family can only be accomplished with the help of a good marriage. Accordingly, marriage is an important part, and significant matter of domestic discipline and children should be educated by parents in this matter.

Parents are responsible for providing the requirements of marriage. Actually, ideal primary education should be given to children by their parents and their duties are fulfilled by providing them with a job and helping them to marry.

References:

1. Ibn-e Fazl-e Tabarsi, Makarim Al Akhlaq, p. 115.
2. Muhammad ibn Ya‘qūb al-Kulaynī, Furū al-Kāfī, vol 6, p. 187.
3. Abul Qasem Payandeh,  Nahj-al feṣāḥa , p. 447.
4. Muhammad ibn Ya‘qūb al-Kulaynī, Rawda al-Kafi , vol 6, p. 47.
5. childrens rights in Islam
6. Fattal Neyshaburi , Rawdat al-wa'izin , p. 369.