Do I need to teach my baby to sit?

The question, asked plainly

Do you train a baby to sit, or does she figure it out herself?

She figures it out. What you can do is give her the conditions, and the most useful of those is time on the floor.

How it actually arrives

It builds out of tummy time. Pushing up on her arms develops the back and neck strength that sitting needs, so the two aren't separate projects.

Then comes tripod sitting — propped forward on her own hands, wobbling, lasting a few seconds. Then longer. Then hands free. Then being able to get into sitting on her own, which is a later and separate skill.

Roughly five to eight months corrected for unsupported sitting, with a wide range either side.

We watched ours rolling well and not moving towards sitting at all, and asked why. The answer is that rolling and sitting develop in parallel rather than in sequence, and one doesn't lead to the other.

The thing not to do

Propping her upright in seats and supports for long stretches.

It looks like practice and it isn't — she's being held in position by the chair rather than by her own muscles, so she gets the appearance of sitting without building any of the strength. It also takes away floor time, which is where the actual work happens.

Straight legs, poor balance, and toppling sideways are all normal parts of learning. Toppling is how she learns to correct.

Cushions around her rather than behind her, so a fall is soft in any direction. And let her fall. Catching her every time removes the lesson.

Not sitting unsupported by around nine months corrected, check with a doctor.

A strong and consistent preference for one side, or one side not being used.

Legs that are very stiff or very floppy compared to the other.

And a skill that's been lost rather than not yet gained. That one always gets mentioned, whatever it is.