Children need to know around 50 words before they will be ready to start building sentences.
Young children learn to build sentences by listening to others; often this skill develops rapidly after they have learned to link 2 or 3 words together.
They will make lots of mistakes along the way and rely on adults modeling correct sentences and sometimes correcting mistakes in a supportive way appropriate to their age and stage of development.
Here we share 12 sets of exercise for sentences construction for the kids for free.