Teaching retelling is a joint work of an adult with a child. Children need to be shown the algorithm for working on the text, teach memorization methods, as well as formulating their own thoughts. Move from simple to complex, gradually minimize your help, be patient and kind, and you will teach your child to retell.
Start by reading simple, child-friendly text. Preschoolers and younger students are better off offering a fairy tale or a short literary work. If your child can read, ask them to read it aloud. Older children can use stories or educational texts.
Divide the text into parts - by paragraphs or by meaning. Ask your child one question at a time for each passage. Try to give him the opportunity to formulate the answers himself, but if he cannot, help.
Helping your child answer questions, look for the main words or semantic phrases with him. Using them, make an outline of the text in writing or highlight them in pencil in paragraphs. Don't write big sentences in the outline, use 2-3 words for each paragraph.
Ask your child to retell the text while looking at the reference words. Let it be a short and monosyllabic retelling, do not demand much. Then go back to the study piece together to compare.
As you work through the text a second time, show your child vivid examples that accompany each point in the outline. Expressive definitions, images, metaphors, in a word, everything that will help him remember the meaning and sequence of points. This is especially useful for children of primary school age and anyone with right-brain thinking. Ask your child to do a second retelling, in more detail. Suggest how to formulate extended sentences.
Work on the text a third time to clarify minor details, better understanding and memorization. Then invite your child to retell it on their own. Work together several texts for 3 - 5 days, during which time the child will acquire the skill of independent work with them.