For people to understand that even though her work is completed inside the 4 walls of her living space, she cannot do both work tasks and house-related tasks - like managing the incoming and outgoing deliveries, starting dinner, laundry, or cleaning up. [and that list could go on and on and on...] BONUS: And, if I DO use a break to do some or one of these tasks, it should not be expected that I do them again/the next day/ always from that day forward, so help us God, until death.
For the other 'Working Parent' to grasp the fact that I chose to work at home to be more easily available to take off in an emergency for child-related matters in the daytime hours, does not mean I am not busy. It also does not mean I will not need to make up those hours. I have flexibility - not by luck but because of hard effort to find & remain within the field of remote working, and so yes, I have also tasks to do.
A backup BT keyboard for when your son's cool mist humidifier has been running in your house for 3 days to help fight a cold and so the keyboard of your laptop randomly refuses to respond for 12 hours. [Tip: I placed the laptop open upside down in a tent shape and let it dry out with the fan on it and then it returned to work. This is very unlikely to work again, however. Do not try at home. Or, do - but don't come runnin' to me if it kills your laptop. I happen to have an Armageddon, back from the dead twice now already, laptop named Henry. So he's a bit special. And slow.]