Learn Hardcore Russian: Сегодня утром я взяла швабру, губку и моющее средство и убрала кухню. - This morning I took a mop, a sponge, and a cleaning product and cleaned the kitchen.

Same rule: past tense agrees with the subject. Since the speaker is presented as female (because of взяла), the second past verb is also feminine: я убрала = I cleaned up.

What case are швабру, губку, моющее средство in, and why?

They’re in the accusative case because they are the direct objects of взять (to take).

швабра → швабру (accusative singular)
губка → губку (accusative singular)
моющее средство is neuter and inanimate; its accusative singular looks the same as nominative: моющее средство.

Why does моющее средство not change form like швабру and губку?

Two reasons:
1) It’s neuter singular.
2) For inanimate nouns, the accusative = nominative in many patterns.
So средство stays средство in the accusative. (The adjective моющее also stays the same for neuter nominative/accusative singular.)

What does моющее mean grammatically here?

моющее is an adjective-like form (a present active participle used adjectivally) meaning cleaning / washing / detergent. It agrees with средство (neuter, singular):

моющее средство = a cleaning agent / detergent

Why is it утром and not утро or в утре?

утром is the common Russian way to say in the morning using the instrumental case as an adverbial time expression.

утро = morning (dictionary form)
утром = (in the) morning (time adverb)
You can also say сегодня утром without any preposition; that’s a standard fixed pattern.

Why is there no preposition like в (as in “in the morning”)?

Russian often expresses time without a preposition, especially with words like утром, вечером, днём, ночью.
So сегодня утром naturally means this morning.

Why are both verbs perfective (взяла, убрала)?

Perfective aspect is used for completed, one-time actions in a sequence. Here the idea is:
1) she took the supplies (completed)
2) she cleaned the kitchen (completed)
Imperfective would focus more on the process/habit (e.g., брала, убирала) rather than the finished result.

What’s the difference between убрала кухню and убирала кухню?

убрала кухню (perfective) = she cleaned the kitchen (and finished)
убирала кухню (imperfective) = she was cleaning / used to clean the kitchen (process, duration, or repeated action)

Does убрать кухню specifically mean “to tidy up,” “to clean,” or “to put away”?

убрать is broad and often means to tidy up / clean up. With a room as the object (кухню), it commonly means to clean/tidy the kitchen (put things away, wipe surfaces, etc.). Context decides how deep the cleaning is.

Why is the word order like this, and can it be changed?

Russian word order is flexible because cases show roles. Сегодня утром я взяла... и убрала кухню is neutral and clear: time → subject → actions.
You can change it for emphasis, e.g.:

Я сегодня утром взяла... (emphasis on I)
Кухню я убрала... (emphasis on the kitchen)
But the given order is a very natural default.

Why is there no comma before и in the list, but the sentence still reads fine?

In Russian, items in a simple list are separated by commas: швабру, губку и моющее средство (no comma before the final и in standard punctuation).
Then another и links the next action: ... средство и убрала кухню. It’s common to repeat и like this when describing a sequence.