user143: I've seen pictures online of young children dressed in monks robes in Buddhist countries. Does someone make the decision on behalf of the child that they will become a monk? Do they eat only one meal a day as adult monks do? Are very young monks also called Venerable Sir? Thanks for helping a western mind to understand this matter. 

user-1: Householder Robin, interested,
Thanks for helping a western mind to understand this matter. is a good approach, Sadhu.
Thousands of gifted young people have anew ordained the last days in traditional countries and will enter their first Vassa, rains, tomorrow, dwelling good time near the tradition of the Noble Ones, take on follow the Arahats.
Today, sort entering a near monastery, my person was approached by a young Venerable who did many years as lay attendance service for the Venerable there, yount and old, now himself most joyfull and proudly monk, here still as Upasaka, guiding to Venerables to the remote cave.

Does someone make the decision on behalf of the child that they will become a monk?
A young person, "child", may develope such desire for himself and ask his parents for allowing leaving home and join the near of the Sangha.
Parents may encourage their children to live a life in the near of the Sangha and renounce. How ever, althoght not always the way, the child himself, at least formal verbal, has to ask a Bhikkhu for going forth under the Tripple Gems.
The cases of allowance by the Buddha to accept younger are often related to devoted followers children, also cases where those became orphans and tended to seek refuge under their parents near monastic teacher.
There have been also cases, at the Buddhas time, today as well, where parents seeked for a pleasing, secure life for their children and such use, for just educational purpose and later good conditions for lay-life are often the reason why children are send to train as novices. Some also dedicate one child for the religion, some take it as way out of poorness. There are as many ways and reasons as there a Novices.
In traditional countries, at least till some years ago, it was usus to get a while ordained as monk in the youth, at least to prevent the tradition and gain good behaviour in speech and body, learn the broad ways of good respect and conduct.
Some origin stories related to ordain younger people, children, from the Mahavagga: 

Mv I 36: Upālidārakavatthu — The Story of the Boy Upāli
Mv I 37: Ahivātakarogavatthu — The Case of Plague
Mv I 41: Rāhulavatthu — The Case of Rāhula

Do they eat only one meal a day as adult monks do?
Technical they could eat from sun-rise till noon. Meal in the morning and short before noon are usual provided and prepeared. There are such as "medicine" allowed nourishments and it would not be of disadvantage bodily in most cases.
Are very young monks also called Venerable Sir?
Yes! Venerable Sir, Bhante,... One sould be clear that such even young person could be a holy men, even an Arahat. Even parents, family, friends... would never be dare to not, at least by speech and body gesture, regard the young as sublime and worthy of reverance person. Even the King would sit lower and bow down (of course if not just behaviour like village children). Other monks would address them as well proper and diverent to lay people.
Only the meditation focusing branch within the Mahanikaya Bhikkhus (incl. the western famous Ajahn Chah groups), those not well informed in Vinaya, tradition and dangers, would not highly regard homeless under the Tripple Gems, just regard them as kind of slaves, good branches of the Mahavihara branch as well as the Dhammayut branch act very careful and Dhamma-Vinaya regarding. For lay-people there is no difference in regarding at all, and even in the times of the Buddha lay people criticized those Bhikkhus not looking after their "sons" in proper ways, not to speak about the Buddhas rebukes toward them.

from the Dahara Sutta: Young
..."There are these four things, great king, that shouldn't be despised & disparaged for being young. Which four? A noble warrior, great king, shouldn't be despised & disparaged for being young. A snake... A fire... And a monk shouldn't be despised & disparaged for being young. These are the four things that shouldn't be despised & disparaged for being young."
That is what the Blessed One said. Having said that, the One Well-Gone, the Teacher, said further:
You shouldn't look down on
      — for being young —
  a noble warrior of consummate birth,
  a high-born prince of great status.
  A person shouldn't disparage him.
For it's possible
  that this lord of human beings,
  this noble warrior,
  will gain the throne
  and, angered at that disparagement,
  come down harshly
  with his royal might.
  So, guarding your life,
      avoid him.
You shouldn't look down on
      — for being young —
  a serpent you meet
  in village or wilderness:
  A person shouldn't disparage it.
As that potent snake slithers along
      with vibrant colors,
  it may someday burn the fool,
  whether woman or man.
  So, guarding your life,
      avoid it.
You shouldn't look down on
      — for being young —
  a blaze that feeds on many things,
  a flame with its blackened trail:
  A person shouldn't disparage it.
For if it gains sustenance,
  becoming a great mass of flame,
  it may someday burn the fool,
  whether woman or man.
  So, guarding your life,
      avoid it.
When a fire burns down a forest
  — that flame with its blackened trail —
      the shoots there
      take birth once more
  with the passage of days & nights.
      But if a monk,
  his virtue consummate,
  burns you with his potency,[1] 
  you won't acquire sons or cattle
  nor will your heirs enjoy wealth.
  They become     barren,
              heir-less,
  like palm tree stumps.
So a person who's wise,
  out of regard for his own good,
  should always show due respect
  for     a serpent,
      a fire,
      a noble warrior with high status,
  &   a monk, his virtue consummate.

At least a inspiring, living,  Khmer folk tale "The story of Bhikkhu Sok"
Some stories possible inspire rejoicing with merits:

Einweihung von zwei jungen Novizen - Ordination of two young novices DEVATUTAS
Einweihung eines Samanera - Ordination of a Samanera (Ayung 01/2016)
Maha Mangala Sutta - មង្គលសូត្រ khmer Rezitation, blessing for you from Ven. fellows, for their ancestors dwelling in modern world in the internet (2014).



...9. "Patience, obedience, meeting the Samanas (holy men), and timely discussions on the Dhamma — this is the highest blessing....

A possible extended and revised answer, as well as given place for discussion and going more into it, can be found here: [Q&A] Can someone explain about children monks? How to regard young Samaneras?
Anumodana!
(Note that this is not given for trade, exchange, stacks, entertainment and akusala deeds, but as a share of merits and to continue such for release)

user18: Who decides:
Often they are coerced into doing it for a short period of time; other places poverty drives them to ordain. In rare cases they do it of their own volition because of some wholesome supporting condition.
Eating:
Monks can eat technically eat two meals as long as it's in the morning hours from dawn to noon. Most monks fall into that schedule. Samanera (novice monks, usually under 20 years of age) often break this rule, eating in the evening, even though it's against the rules.
How they are called:
It depends on the country. In Sri Lanka, some samanera never actually become bhikkhus (fully ordained), so there is a tendency to call them all by the same honorific. In Thailand they are called "nen", as opposed to "pra", and they only wear two robes instead of three. I don't think there is a case of a samanera being called Bhante, which would be the equivalent of "venerable sir" in the Pali. From a monastic point of view, they are still considered unordained, and they only keep ten rules.

user64: In Thailand, male novices (called nen or samanera) are a fairly common sight.  Very often they have taken vows only temporarily.  They may do it during the phansa (rainy season) period, during summer holidays from March to May, or just for a few days in order to make merit when a parent or grandparent has passed away.  The latter motivation is in a sense repayment of a debt owed to family members for being under their care as a young child.  According to Thai wikipedia, novices should be no younger than 8.  A temple website states that they follow only 10 precepts.  A Thai friend of mine told me that one motivation on the part of parents is that since the boys learn the basics of meditation practice, they are more mature and exhibit fewer behavioral problems when they come out.  I recall reading something like this in a biography of one well-known Thai monk – it might have been Buddhadasa bhikkhu.  
Regarding language, my friend said that some of the special monastic vocabulary (like chan for ‘to eat') is used when speaking to novices as well as monks, but that the overall politeness level is less formal (e.g. novices are not addressed as ‘venerable’.) 
In Burma I have seen young girls (samanerī or the Burmese equivalent) in pinkish robes out on alms rounds, perhaps later in the morning than monks.  You wouldn’t see that in Thailand though.
Donald Swearer discusses additional motivations for ordaining as a teenager in his book ‘The Buddhist World of Southeast Asia’ (1995), p. 48:

In Thailand one of the principle reasons for being ordained is to acquire an education.  Among poorer families often children cannot afford to attend school.  Ordination as a novice provides for their material needs as well as a basic education.  Indeed, if a boy is bright and highly motivated he may complete secondary school as a novice or monk, graduate from a monastic college, and then earn an advanced degree from a university in another country, such as India.  After teaching in a monastery school for several years or serving as an administrator in a larger provincial monastery he will probably disrobe and take a responsible and respected secular job.  Although such exploitation of the monastic educational structure siphons off able leadership, it has become standard practice and bears little or no social stigma.

I have known several university teachers who followed this career path - they were all from the relatively poor northeastern region of Thailand. 
Swearer goes on to suggest that in an earlier era, ordaining at the age of puberty was a kind of rite of passage that all males went though.  Monks in fact lead rather comfortable lives and for a child from a poor family, being a monk would mean raising one’s economic and social status.  Given the traditional link between education and the sangha, it should be no surprise that males ordain at a young age and that this is encouraged by local cultural norms.  In comtemporary Thai society the link has been weakened with the advent of universal secular education, but elsewhere in Southeast Asia (Cambodia, Laos and Burma) it is likely still quite strong.

143: <p>I've seen pictures online of young children dressed in monks robes in Buddhist countries. Does someone make the decision on behalf of the child that they will become a monk? Do they eat only one meal a day as adult monks do? Are very young monks also called Venerable Sir? Thanks for helping a western mind to understand this matter. </p>
 -1: <p>Householder Robin, interested,</p>

<p><code>Thanks for helping a western mind to understand this matter.</code> is a good approach, Sadhu.</p>

<p>Thousands of gifted young people have anew ordained the last days in traditional countries and will enter their first Vassa, rains, tomorrow, dwelling good time near the tradition of the Noble Ones, take on follow the Arahats.</p>

<p>Today, sort entering a near monastery, my person was approached by a young Venerable who did many years as lay attendance service for the Venerable there, yount and old, now himself most joyfull and proudly monk, <a href="http://accesstoinsight.eu/_detail/user:johann:gallery:archiv2018:20180625_209-640x481.jpg" rel="nofollow noreferrer">here</a> still as Upasaka, guiding to Venerables to the remote cave.</p>

<p><a href="https://i.stack.imgur.com/H2yMR.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/H2yMR.jpg" alt="enter image description here"></a></p>

<p><strong>Does someone make the decision on behalf of the child that they will become a monk?</strong></p>

<p>A young person, "child", may develope such desire for himself and ask his parents for allowing leaving home and join the near of the Sangha.</p>

<p>Parents may encourage their children to live a life in the near of the Sangha and renounce. How ever, althoght not always the way, the child himself, at least formal verbal, has to ask a Bhikkhu for going forth under the Tripple Gems.</p>

<p>The cases of allowance by the Buddha to accept younger are often related to devoted followers children, also cases where those became orphans and tended to seek refuge under their parents near monastic teacher.</p>

<p>There have been also cases, at the Buddhas time, today as well, where parents seeked for a pleasing, secure life for their children and such use, for just educational purpose and later good conditions for lay-life are often the reason why children are send to train as novices. Some also dedicate one child for the religion, some take it as way out of poorness. There are as many ways and reasons as there a Novices.</p>

<p>In traditional countries, at least till some years ago, it was usus to get a while ordained as monk in the youth, at least to prevent the tradition and gain good behaviour in speech and body, learn the broad ways of good respect and conduct.</p>

<p>Some origin stories related to ordain younger people, children, from the Mahavagga: </p>

<ul>
<li><a href="http://zugangzureinsicht.org/html/tipitaka/vin/mv/mv01/mv.01.36.khem_en.html" rel="nofollow noreferrer">Mv I 36: Upālidārakavatthu — The Story of the Boy Upāli</a></li>
<li><a href="http://zugangzureinsicht.org/html/tipitaka/vin/mv/mv01/mv.01.37.khem_en.html" rel="nofollow noreferrer">Mv I 37: Ahivātakarogavatthu — The Case of Plague</a></li>
<li><a href="http://zugangzureinsicht.org/html/tipitaka/vin/mv/mv01/mv.01.41.khem_en.html" rel="nofollow noreferrer">Mv I 41: Rāhulavatthu — The Case of Rāhula</a></li>
</ul>

<p><strong>Do they eat only one meal a day as adult monks do?</strong></p>

<p>Technical they could eat from sun-rise till noon. Meal in the morning and short before noon are usual provided and prepeared. There are such as "medicine" allowed nourishments and it would not be of disadvantage bodily in most cases.</p>

<p><strong>Are very young monks also called Venerable Sir?</strong></p>

<p>Yes! Venerable Sir, Bhante,... One sould be clear that such even young person could be a holy men, even an Arahat. Even parents, family, friends... would never be dare to not, at least by speech and body gesture, regard the young as sublime and worthy of reverance person. Even the King would sit lower and bow down (of course if not just behaviour like village children). Other monks would address them as well proper and diverent to lay people.</p>

<p>Only the meditation focusing branch within the Mahanikaya Bhikkhus (incl. the western famous Ajahn Chah groups), those not well informed in Vinaya, tradition and dangers, would not highly regard homeless under the Tripple Gems, just regard them as kind of slaves, good branches of the Mahavihara branch as well as the Dhammayut branch act very careful and Dhamma-Vinaya regarding. For lay-people there is no difference in regarding at all, and even in the times of the Buddha lay people criticized those Bhikkhus not looking after their "sons" in proper ways, not to speak about the Buddhas rebukes toward them.</p>

<blockquote>
  <p>from the <strong><a href="http://zugangzureinsicht.org/html/tipitaka/sn/sn03/sn03.001.than_en.html" rel="nofollow noreferrer">Dahara Sutta: Young</a></strong></p>
  
  <p>..."There are these four things, great king, that shouldn't be despised &amp; disparaged for being young. Which four? A noble warrior, great king, shouldn't be despised &amp; disparaged for being young. A snake... A fire... And a monk shouldn't be despised &amp; disparaged for being young. These are the four things that shouldn't be despised &amp; disparaged for being young."</p>
  
  <p>That is what the Blessed One said. Having said that, the One Well-Gone, the Teacher, said further:</p>
  
  <p><code>You shouldn't look down on
      — for being young —
  a noble warrior of consummate birth,
  a high-born prince of great status.
  A person shouldn't disparage him.</code></p>
  
  <p><code>For it's possible
  that this lord of human beings,
  this noble warrior,
  will gain the throne
  and, angered at that disparagement,
  come down harshly
  with his royal might.
  So, guarding your life,
      avoid him.</code></p>
  
  <p><code>You shouldn't look down on
      — for being young —
  a serpent you meet
  in village or wilderness:
  A person shouldn't disparage it.</code></p>
  
  <p><code>As that potent snake slithers along
      with vibrant colors,
  it may someday burn the fool,
  whether woman or man.
  So, guarding your life,
      avoid it.</code></p>
  
  <p><code>You shouldn't look down on
      — for being young —
  a blaze that feeds on many things,
  a flame with its blackened trail:
  A person shouldn't disparage it.</code></p>
  
  <p><code>For if it gains sustenance,
  becoming a great mass of flame,
  it may someday burn the fool,
  whether woman or man.
  So, guarding your life,
      avoid it.</code></p>
  
  <p><code>When a fire burns down a forest
  — that flame with its blackened trail —
      the shoots there
      take birth once more
  with the passage of days &amp; nights.
      But if a monk,
  his virtue consummate,
  burns you with his potency,[1] 
  you won't acquire sons or cattle
  nor will your heirs enjoy wealth.
  They become     barren,
              heir-less,
  like palm tree stumps.</code></p>
  
  <p><code>So a person who's wise,
  out of regard for his own good,
  should always show due respect
  for     a serpent,
      a fire,
      a noble warrior with high status,
  &amp;   a monk, his virtue consummate.</code></p>
</blockquote>

<p>At least a inspiring, living,  Khmer folk tale "<a href="http://sangham.net/index.php/topic,370.msg2049.html#msg2049" rel="nofollow noreferrer">The story of Bhikkhu Sok</a>"</p>

<p>Some stories possible inspire rejoicing with merits:</p>

<ul>
<li><p><a href="http://sangham.net/index.php/topic,2198.0.html" rel="nofollow noreferrer">Einweihung von zwei jungen Novizen - Ordination of two young novices DEVATUTAS</a></p></li>
<li><p><a href="http://sangham.net/index.php/topic,2090.0.html" rel="nofollow noreferrer">Einweihung eines Samanera - Ordination of a Samanera (Ayung 01/2016)</a></p></li>
<li><p><a href="http://sangham.net/index.php/topic,1426.0.html" rel="nofollow noreferrer">Maha Mangala Sutta - មង្គលសូត្រ khmer Rezitation</a>, blessing for you from Ven. fellows, for their ancestors dwelling in modern world in the internet (2014).</p></li>
</ul>

<p><a href="https://i.stack.imgur.com/rMUdp.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rMUdp.jpg" alt="enter image description here"></a></p>

<blockquote>
  <p>...9. "Patience, obedience, meeting the Samanas (holy men), and timely discussions on the Dhamma — this is the highest blessing....</p>
</blockquote>

<p>A possible extended and revised answer, as well as given place for discussion and going more into it, can be found here: <a href="http://sangham.net/index.php/topic,9361.msg19271.html#msg19271" rel="nofollow noreferrer">[Q&amp;A] Can someone explain about children monks? How to regard young Samaneras?</a></p>

<p>Anumodana!</p>

<p><em>(Note that this is not given for trade, exchange, stacks, entertainment and akusala deeds, but as a share of merits and to continue such for release)</em></p>
 18: <p><strong>Who decides:</strong></p>

<p>Often they are coerced into doing it for a short period of time; other places poverty drives them to ordain. In rare cases they do it of their own volition because of some wholesome supporting condition.</p>

<p><strong>Eating:</strong></p>

<p>Monks can eat technically eat two meals as long as it's in the morning hours from dawn to noon. Most monks fall into that schedule. Samanera (novice monks, usually under 20 years of age) often break this rule, eating in the evening, even though it's against the rules.</p>

<p><strong>How they are called:</strong></p>

<p>It depends on the country. In Sri Lanka, some samanera never actually become bhikkhus (fully ordained), so there is a tendency to call them all by the same honorific. In Thailand they are called "nen", as opposed to "pra", and they only wear two robes instead of three. I don't think there is a case of a samanera being called Bhante, which would be the equivalent of "venerable sir" in the Pali. From a monastic point of view, they are still considered unordained, and they only keep ten rules.</p>
 64: <p>In Thailand, male novices (called <em>nen</em> or <em>samanera</em>) are a fairly common sight.  Very often they have taken vows only temporarily.  They may do it during the <em>phansa</em> (rainy season) period, during summer holidays from March to May, or just for a few days in order to make merit when a parent or grandparent has passed away.  The latter motivation is in a sense repayment of a debt owed to family members for being under their care as a young child.  According to Thai wikipedia, novices should be no younger than 8.  A temple website states that they follow only 10 precepts.  A Thai friend of mine told me that one motivation on the part of parents is that since the boys learn the basics of meditation practice, they are more mature and exhibit fewer behavioral problems when they come out.  I recall reading something like this in a biography of one well-known Thai monk – it might have been Buddhadasa bhikkhu.  </p>

<p>Regarding language, my friend said that some of the special monastic vocabulary (like <em>chan</em> for ‘to eat') is used when speaking to novices as well as monks, but that the overall politeness level is less formal (e.g. novices are not addressed as ‘venerable’.) </p>

<p>In Burma I have seen young girls (<em>samanerī</em> or the Burmese equivalent) in pinkish robes out on alms rounds, perhaps later in the morning than monks.  You wouldn’t see that in Thailand though.</p>

<p>Donald Swearer discusses additional motivations for ordaining as a teenager in his book ‘The Buddhist World of Southeast Asia’ (1995), p. 48:</p>

<blockquote>
  <p>In Thailand one of the principle reasons for being ordained is to acquire an education.  Among poorer families often children cannot afford to attend school.  Ordination as a novice provides for their material needs as well as a basic education.  Indeed, if a boy is bright and highly motivated he may complete secondary school as a novice or monk, graduate from a monastic college, and then earn an advanced degree from a university in another country, such as India.  After teaching in a monastery school for several years or serving as an administrator in a larger provincial monastery he will probably disrobe and take a responsible and respected secular job.  Although such exploitation of the monastic educational structure siphons off able leadership, it has become standard practice and bears little or no social stigma.</p>
</blockquote>

<p>I have known several university teachers who followed this career path - they were all from the relatively poor northeastern region of Thailand. </p>

<p>Swearer goes on to suggest that in an earlier era, ordaining at the age of puberty was a kind of rite of passage that all males went though.  Monks in fact lead rather comfortable lives and for a child from a poor family, being a monk would mean raising one’s economic and social status.  Given the traditional link between education and the sangha, it should be no surprise that males ordain at a young age and that this is encouraged by local cultural norms.  In comtemporary Thai society the link has been weakened with the advent of universal secular education, but elsewhere in Southeast Asia (Cambodia, Laos and Burma) it is likely still quite strong.</p>
