The Duchess of Cambridge will sympathise with schoolchildren across the country when she joins an online assembly and says “It’s been a really difficult time for us all”.

Kate will tell youngsters logged in to the virtual school hall that they may feel “frustrated” at the restrictions imposed during the coronavirus lockdown but the feelings “won’t last forever”.

The duchess will deliver her words of support on Thursday for the Oak National Academy – an online classroom providing video lessons and free resources to parents and teachers.

In the pre-recorded assembly message, the duchess will say: “Today, I wanted to talk to you about the importance of being kind and looking after one another.

“We all have our ups and down, especially when things change in our lives as they have in so many ways recently. This can cause us to have a huge range of different feelings. Sometimes these feelings may be good, but sometimes they may be uncomfortable, and we feel worried, angry or upset.

“Being unable to see your friends or spend time with your family will undoubtedly be frustrating for you, just as it is for them. It’s been a really difficult time for us all.

“But it’s important to know that these feelings and frustrations are totally normal, and that they won’t last forever. Talking to someone – whether it’s a friend, family member or teacher – is something you can do to make yourself feel that little bit better.

“And you can also play your part in helping others feel better too. Whether offering a friendly ear, or helping someone in need. Small acts of kindness can go such a long way.

“But as we help others, we mustn’t forget to nurture ourselves by taking the time to focus on the things that make us feel happy too. This might be playing our favourite game, being outside, or talking to our friends. They all help with our mental wellbeing.”

The online classroom was created in response to the lockdown and supports teachers educating their pupils remotely, and since its launch has delivered more than 12 million lessons to children and young people.

The Oak National Academy is part of the Reach Foundation, a charitable organisation founded by philanthropists Mark and Wendy Wilson to help children in need, and the online resource describes itself as a community of school leaders, teachers and supporting team members.

Every Thursday morning it hosts assemblies for students across the UK, allowing them to experience the normal routine of a school environment.

During the virtual assembly Kate chatted to five children, aged from five to nine, from Waterloo Primary Academy in Blackpool, whose parents have been working on the frontline during the coronavirus pandemic.

Quizzing them about their own acts of kindness, she also admired photographs of each of them, taken for her Hold Still project, showing them making rainbows out of PE equipment, tidying up the art and craft supplies, handing out dinners and sharing their toys.

When Kate asked the youngsters: “And what do you think…if a friend of yours is really kind to you, how does that make you feel?” They replied: “Really happy.”

She quizzed them further, “And does it make you happy if you’re kind back?” and was told “yes”.

The duchess said: “It’s true isn’t it? So many times when we do things for other people, it makes us feel really good about ourselves.”

Mark Hamblett, head teacher at Waterloo Primary Academy, said they only told the children that Kate would be delivering a message a few minutes before the assembly, which was recorded on June 10, so they would not be nervous.

Mr Hamblett said: “I couldn’t be more proud of them. The last few months and weeks have been so difficult to navigate, and the children have been incredible.”