Parents are worrying that a shortage of places is creating "supersize" primary schools, according to the Netmums website.
A surge in the birth rate in some areas has meant a rapid expansion of schools, with temporary classrooms added.
A survey of mothers' experiences on Netmums found concerns about children being "overwhelmed" at big schools.
Parents reported their reservations about primary schools that in some cases now had more than 700 pupils.
"The rising birth rate means we are seeing the birth of mega primaries," said Netmums' founder, Siobhan Freegard.
Official forecasts last month showed that an extra 450,000 primary places will be needed in England between 2010 and 2015.
Many local authorities are under pressure to find room for such an expansion - such as building temporary "bulge" classrooms.
But the Netmums website says there is disquiet among parents - with fears that expansion will change the character of primary schools and the pressure on places will make it harder to get a first choice place.
More than a thousand parents contributed to a discussion about the places shortage.
Although not a representative sample, it showed parents voicing concerns about schools with a one-form entry becoming schools with a two- or three-form entry.
In some cases, parents said there were now up to five primary classes in a single year.
"It can make smaller children feel overwhelmed," said one of the Netmums contributors, who expressed concern about less attention to individual pupils and fears about bullying and gangs.
"I think that big schools will definitely affect some children, especially quiet, less confident kids," wrote another.
"Our city has increased so much in the last six-seven years, but building one more small school was nowhere near enough judging by the struggle for places."
There were other parental concerns - such as children not being known individually, siblings having to attend different schools and a shrinking catchment area.
"Large schools make sense from a money wise and business point of view but I've seen children in reception look overwhelmed just going into their door, as there are 89 other children in their year.
"School has amazing facilities due to its high numbers and good funding - but I'm not sure good facilities compensate for children feeling more secure in a smaller school environment," said a Netmums comment.
But there are also parents who prefer a bigger school, including from a parent whose child is at a primary school with 840 pupils.
"Depends on the school and the child. If the large school is a good one, I don't think it disadvantages the child, quite the opposite. The school where my son is in the nursery class has nearly 700 pupils and this will increase to 840 as it is now a four-form entry.
"The children say it doesn't feel like a big school because of the way it has been organised. For example, staggered starting and finishing times, separate playgrounds for nursery, reception, infants and juniors.
"Being a large school, they also offer a number of specialised teachers, they have a swimming pool and various after-school clubs on-site."
The shortage of places in primary schools reflects a growth in the birth rate - with some areas facing an increase of 25% or above in the primary school population. It also means that in a few years secondary pupils will face a similar surge in demand.
In Barking in east London, with one of the biggest increases, there will have to be places found for an extra 8,000 primary pupils by 2015.
The council has been considering converting disused commercial buildings into classrooms - or even more radical responses such as the split-shift use of schools.
But in many cases the response has been to expand the existing schools.
As well as a rising birth rate, there have also been demographic changes, with families being drawn into areas by employment or new housing developments.
Although much of the attention has been on London and other major cities, there are also concerns in other parts of the country.
A protest group of parents in Winchester in Hampshire has been lobbying over a lack of places and the impact that is having on parental choice.
Netmums' Siobhan Freegard warns that the increase in demand for places is at a time of budget pressures on local authorities.
"Set this against cuts to the school building programme and we have a perfect storm where more kids will be crammed into bulge classes in schools designed for far fewer pupils.
"Both parents and teachers have raised fears it will affect pupils learning - so the government needs to take action and invest funds now."
The government has already announced that it will create more places in response to the shortage - with £4bn to be invested over four years in the places under the greatest pressure.
A Department for Education spokesman said: "Many areas are dealing with an unprecedented rise in primary numbers - back up to levels last seen in the 1970s.
"No-one is saying it will be easy balancing demand for places with retaining the sort of character and ethos that parents want. Our job is to put the capital investment in place so councils and schools can make the right decisions."
Are any of your local primary schools above 700 pupils? Are you concerned about size of primary schools? Do you have problems with a shortage of school places?
I teach in a six form entry junior school. We are huge and as a result can offer groupings for Numeracy, Literacy and Spellings. We also rotate children so they are taught by subject specialists for Art, RE, PE, ICT and Music. However....do I know the name of every child in my school?..no. Not even every child in my year group. That is the sad flip side. It makes it very hard to deal with discipline issues at playtime as you have no idea who the children are or even which class they are in. Would I want my own child in a school my size? No.
I went to a big primary school in Bristol, between 700 and 800 pupils and rapidly expanding (by the time my brother went there, there were 4 classes per year.) Whilst I was there, it didn't feel like a big school, as time went by teachers did learn your names, maybe compared with a little country school it was big, but I think that being in a bigger primary helps your social skills and minimizes the leap from primary to secondary. Would I recommend it to someone deciding for their child, which is better? Yes.
I teach at a 4 form entry primary in greater London. That means 120 children per year over years R (reception) to 6. It is a big school and we have recently come through and Ofsted with flying colours. I'm proud of the diversity of our children and the facilities we can provide. We can cater to all children, from the brightest to those with special needs or beginners of English. We have a broad and enriched curriculum, extensive extra-curricular activities, the foremost technologies, and even school chickens! When I went into teaching I was advised to apply for jobs at the larger city schools because they are at the front of innovation and spending. I agree. Having seen the local village school in Suffolk where my dad lives, whilst it is ideal in some regards with its 80 pupils over 7 years from what I can gather it does not have our experiences, our budget (will they have a bevvy of Olympic athletes coming to visit the children?) and certainly does not have teachers who can handle the behaviours that are appearing across all areas of society, regardless of geographic location. We can and our results and skills reflect this.
My 5 year old is part of an intake of 90 - but there are only 2 classrooms. Promised a 3rd classroom but no signs of any building work yet...
EG , Bucks
I work in a four form entry primary school in Redbridge, which is moving towards being a five form entry school next year. Not all members of staff are for the increase in size but most are. We have one of the best resourced libraries in the borough and are one of only a few primary schools to have its own Drama room. The increase in budget also allows us to have a dedicated Drama teacher (great to help with English through speaking and listening) and also a Music specialist and higher than average TA ratio within the school. Size is only an issue if the staff, parents and community allow it. We have to work extremely hard to make sure ALL children and adults feel part of the school. This is by no means an easy feat but definitely worthwhile as the pluses far outweigh the minuses.
My boys are separated into two different first schools within the same county due to 37 first place applications for 30 places. Only one reception class in the school. Previous two years there was only an intake of around 20.
Please explain how one lesson every two week in a special room or with a specialist music teacher compensates for my teachers not knowing my name or which class I am in.
I think the size of the school does not matter that much. What matters is whether the leadership of the school and the teaching is any good. Do all pupils make good progress? Obviously, all pupils need to feel happy ideally and also to feel part of the school, and also feel they are able to learn. If the leadership and teaching is good for all pupils, then children can have a very positive experience in a big school with more facilities. Some schools have problems with weak leadership and poor teaching especially for the struggling pupils, and this is a much worse problem than having a large school.
Why does the need for school places seem to come as a surprise for local authorities? Children are almost five when they go to school so the plans for the correct number of schools and classes should be done when the chidren are born not the year before they are due to start school. The crazy panic when there aren't enough places, the dash to secure funding, the use of portacabins, it's all stupid. The village I lived in a few years ago had 1,000 new houses built and all sold to young couples yet the baby boom surprised them and they had only 30 school places for 100 children the summer before they were due to start school. These children had been in the village 4 years by then yet nobody noticed or planned for a school for them so they were in portacabins for 3 years while funding was secured. It should have been secured when they were born. Start planning ahead.
I moved my son from a small school to a large, 4 form entry primary at the end of reception and it is the best thing I have ever done. He was making very little progress at the other school and was bored and unhappy. At the larger school, which is as other contributors have said, advantaged by better systems, more staff and specialists, a newer site and in my opinion a better quality of staff, he is thriving. A school is made outstanding by the staff, the systems and the focus on the individual child - not the size alone. An outstanding school will use their systems and staff to ensure that each child is well catered for and this is certainly my experience.
Gail, West London
This is absolutely outrageous that class sizes are only going to increase, when there are thousands upon thousands of qualified teachers that cannot find work.
It is not a suprise. They close schools as soon as there is a drop in pupil numbers and then panic and say we need to open a new school because numbers are increasing again! They can't build new schools or classrooms quick enough so resort to putting up prefabs which end up staying much longer than they designed for. Finally the extension classroom or new school gets built and then, yes you've guessed it, the birth rate has changed again and they are planning another closure! Authorities should be forced to keep schools open with small class sizes to allow for further expansion in later years, as surely this must work out cheaper than constant closure and rebuilding of schools!
My son goes to a huge primary school - 6 forms in each year. I am baffled by the suggestion that his teachers do not know his name - of course they do! The head of year knows them all too. Once they are in their own classroom it is the same as anywhere else. My son started in reception as rather shy but the environment has really brought him out of himself and I have been impressed at the level of attention to individual targets for different children. Size of school is not necessarily an issue at all, it's quality: of teaching and care.
I am an ICT network manager at a local school. We are the largest primary school in the borough. We are increasing to five forms of entry, our predicted pupil entry in 2014 will be 1240 pupils. That means we will be one of the largest primary schools in the London area. I have & see no problems with this, we have an Ofsted outstanding grade and have achieved this by having excellent staff & learning resources. As we are such a large school, the funding we receive reflects this, allowing us to invest in the best possible resources for our children. Unlike our current government believes, ICT is now a basic eduction requirement. Technology is now part of our everyday life and younger generations adapt the skills at a very young age. Schools need to be adequately equipped to keep up with today's lifestyle. ICT can be an expensive resource and this budget increase allows us to invest in new technology for students to learn.