The UK's various coronavirus lockdowns are said to have affected children's speech and language skills, however, simple steps can help to get a youngster's development back on track.
A team from the Education Endowment Foundation (EEF) analysed a survey completed by officials at 58 primary schools across England.
Just over three-quarters (76%) of the schools claim the children who started in the most recent autumn term required more help than in previous years.
"Communication and language development" is a particular issue, with nearly all (96%) of the schools being "very" or "quite concerned".
Enforced home schooling combined with no play dates, social distancing and adults wearing face coverings is thought to have reduced a child's opportunities to engage in conversations and increase their vocabulary. Youngsters from deprived backgrounds are expected to be worst affected.
Poor speech is said to impact a child's ability to learn and perform well at school. The UK government is therefore due to invest £18m ($25m) in early-years catch-up.
"The findings from our research are undoubtedly concerning," Professor Becky Francis, chief executive of the EEF, told Yahoo UK.
"We know the development of early language and communication is crucial in laying the foundations for children to learn and achieve later in life.
"Supporting young pupils to recover from the effects of lockdown is possible and now schools have reopened fully, teachers and school leaders are already capitalising on opportunities to restore learning."
How to spot if your child's speech has been affected by lockdown
There are no set warning signs that a child's speech has been affected by the extreme restrictions, with a youngster's language skills varying significantly according to their age.
Amy Loxley, a speech and language advisor at the children's communications charity I CAN, recommends parents look out for any change in their child's speech or understanding.
"When they start interacting with other children, they [parents] might notice their child isn't at the same level," she told Yahoo UK.
"[It could be that] their vocabulary is more immature, their sentences are a bit shorter or simpler, [or] when they're trying to express themselves they may sound more jumbled."
A child may struggle to follow instructions as easily as their peers or come across like they are not listening when spoken to.
The youngster may then act up out of frustration. "They can't express what they want or what's wrong," said Loxley.
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How to help an affected child
Loxley recommends parents set aside time every day to talk to or play with their child.
"Even 10 minutes a day can make a real difference," she said. "[It should be] uninterrupted time where they're [parents] paying full attention to their child."
Reading books has been shown to boost a child's language skills. Try to choose a book on a topic that interests the child, whether it be pirates, monkeys or princesses.
"It doesn't have to mean reading all the words," said Loxley. "It could involve them [the child] turning the pages."
Loxley also recommends trying "touchy feely" books, which have different textures and flaps that may capture a youngster's attention.
If eating dinner as a family, Loxley suggests discussing the taste, texture and look of the meal.
"[A parent could say] 'This pizza's really hot, blow on it. I like the mushrooms, daddy likes the tomatoes'," she said.
Speech and language therapist Ele Leatherbarrow from Speech Wise agrees, adding: "The most effective language learning happens in real-life situations where the child can hear words relating to what they are doing and thinking about at that time.
"The best way to support language development is just to talk to your child about whatever it is they are doing – putting their coat on, having a bath, walking to school," she told Yahoo UK.
A concerned parent may be tempted to use complex language, in an attempt to boost their child's vocabulary.
Loxley has warned this can be overwhelming for the child, likening it to an adult being in a foreign country where everyone is speaking quickly in a language they do not understand.
If the locals slow down and use simpler words, a tourist may find the conversation easier to follow.
"We don't have to talk to young children like they're adults," said Loxley.
"Think 'what level is my child at?' Keep your language around that level or one step higher."
Leatherbarrow has also stressed any complex words should be explained to a child.
"Give them time and space to talk back, and elaborate slightly on what they say by adding an extra word or something slightly more complex," she said.
For example, "if they say 'big bus' you could reply 'yes, a huge bus'," added Leatherbarrow.
Where to get professional help
Concerned parents can check their child's development against what is expected for their age via I Can's progress checker.
The charity also has a free enquiry service where parents can speak to a qualified speech and language therapist. Call 020 7843 2544 or email email@example.com to book a 30 minute phone consultation. The therapist will then recommend the next course of action.
Leatherbarrow also advises concerned parents speak to their child's nursery or school, which may be able to provide additional support.
Whether the speech defects are mild or severe, Loxley has stressed parents should not beat themselves up.
"Parents can feel blamed for their children's difficulties," she said. "It's not the case.
"Some children need a bit more help than others."
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