Because magic
"Yes, she does that from time to time. That's why we don't have any hanging lamps in this house."
Toddlers are brimming with raw energy, and toddler sorcerors are no exception. Since they don't have the concentration to meditate or cast spells, this is how it comes out: By flying randomly around the room until it wears off.
Magic requires solitary practice. A lover and a toddler is pretty much the worst combination for this, except perhaps more toddlers or lovers. They keep wanting your attention, and they are just too cute to refuse. See, this is why most monastic orders insist on celibacy, most witches' covens are female only, and most C programmers are virgins well into their 30es. OK, the last one is kind of unofficial.
(Oviously the "female only" thing did not work here, as these two are flirting like crazy if I leave them alone. Their romantic relationship is much stronger than their friendship. If they are not checking on the toddler, they are checking out each other.)
Kari specializes in White Arts, known in some circles as theurgy (divine work). It consists here of 3 branches: Creation, Empowerment and Deification. Empowerment focuses on helping others, Deification focuses on helping yourself, and Creation focuses on improving the world around you. The small sun indicates that a Creation spell is being cast, in this case to lock the freshness of food so it doesn't decay even if left out of the fridge. She also just improved its quality in several steps from poor to excellent.
This practical use of sorcery counts as practice in terms of improving your branch skills and leveling up to gain new spells. But it drains your magical energy, and this needs to be refilled.
Recharging the "magical connection" is done through a special "practice". However, I believe this may not be necessary for hybrid sorcerers like Liisa when she grows up, or for sorcerers who pick the Ritual of Neutrality. As far as I know, their power is always maxed, but they don't get bonuses for light or dark specialization. Also they don't get needs bonuses. Kari has to refill her magical connection (for now at least) but she never needs to sleep or shower. It is a pretty complex system with bonuses and costs depending on your choices, both when you become a sorcerer and later.
And we end the day with Kari healing Annika who's got a stomach flu. When you cast a Light Sorcery spell on someone, an aura of light will envelop both of you. In addition to practice in Empowerment sorcery, Kari gets a small amount of positive fame since I have the Get Famous expansion pack. Ironically I've never seen Eaxis' own Realm of Magic interact with the fame system. But then again, sorcery has more spells that directly helps or harms people (and pets, and plants). A heal spell is something I looked for and didn't find in Realm of Magic, so it is nice to have it again. (We had this in Sims 2, remember?)
We have only scratched the surface of the magic systems, so hopefully we will come back to this in future updates, if any.