Millions of children across England are being asked to contribute to a survey about their hopes for the future.
Children's Commissioner for England Dame Rachel de Souza says the results will inform a review aimed at tackling "generational problems that have held back too many children for decades".
The Big Ask is aiming to be the largest consultation with children undertaken in England.
It will be introduced with an online assembly by footballer Marcus Rashford.
From Monday, the month-long anonymous survey will be made available to schools, youth groups, charities and other children's organisations and services with questions tailored to different age groups.
Children will be asked how happy they are about aspects of their lives, and what they think stops children achieving what they want to achieve when they grow up.
There will be focus groups for children with special educational needs, disabilities or other complex needs, and focus groups to ensure the experience of babies and pre-school children is captured.
Inspired by the 1942 Beveridge Report, which laid the foundations of the welfare state, Dame Rachel says the results will inform a review - titled the Childhood Commission - which will propose solutions to barriers facing children and set targets to monitor improvements.
The 1940s report, written by Liberal economist Sir William Beveridge, was commissioned by the wartime coalition government to examine how Britain should be rebuilt after World War Two and paved the way for major reforms including the creation of the NHS.
Dame Rachel will visit schools across the country to hear first-hand from children about their experiences of the coronavirus pandemic and hopes for the future.
She said she wanted to "better understand what children want from the people in power and those who make decisions about their lives".
Dame Rachel said children's responses would be at the heart of her "'Beveridge-style' blueprint for government".
She said: "It is time to give something back to children after the huge sacrifices they have made during the Covid pandemic.
"The Big Ask will ask millions of children in England to tell us what life is like for them, what their hopes and ambitions are, and what is holding them back."
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