👶 By Age — What's Normal

At 4, a child's thinking changes rapidly – but "normal" here is a wide range, not a checklist. Honestly, from the research: which areas of thinking and knowledge open up around four, what's best to support, and what to keep an eye on – without "should" and without parental anxiety.

Around seven, friendship suddenly gets sharper: "she's not my friend anymore," hurt feelings, splitting into "us" and "them." It's not a breakdown but a side effect of growing up – the child grasps mutuality and exclusion for the first time. What research says changes.

Sharp mood swings, a closed door, "leave me alone" – at 10–13 this is usually normal, not a red flag. From recent research: why it happens (brain, puberty, sleep), what opens up in thinking – and how to tell ordinary teen gloom from signs worth seeing a professional about.