4-week development

"Your baby can now track a moving object with her eyes for longer than a
couple of seconds. Try passing a colorful rattle in front of her face —
you may be rewarded with coos and gurgles of pleasure. Her head is
steadier now too, and she may even be able to lift it up when lying flat
on her stomach. Short periods of time on the floor will help her
strengthen her neck muscles."
Yes. Ethan can do this already.