Since Adam has been visiting a lot recently (and will now be looked after by Olyvia, along with Regan, twice a week), Samuel is able to pick up new skills by observing someone roughly a year older than himself.
This is obviously good in some ways, but bad in others. Sam’s now able to open doors (at least the internal ones here), for example. Obviously a skill that will come in handy later in life, but also a bit of a pain (at least he can’t unlock doors or open the front door yet – although he does have sufficient skills to move something over to the garage door, push the opener, and get out the automatic door).