Met rolmaat en waterpas controleerde hij de plank.

Because the sentence starts with Met rolmaat en waterpas, which takes the first position in the clause. In a normal Dutch main clause, the finite verb must come in the second position.

So:

• Hij controleerde de plank. = neutral word order
• Met rolmaat en waterpas controleerde hij de plank. = the prepositional phrase is moved to the front for emphasis

This causes inversion: the verb controleerde comes before the subject hij.

A useful pattern to remember:

• Hij controleerde...
• Gisteren controleerde hij...
• Met rolmaat en waterpas controleerde hij...

Dutch often leaves out een in short, tool-like expressions after met, especially when the speaker is talking about the means used rather than introducing specific individual objects.

So met rolmaat en waterpas means something like:

• using a tape measure and spirit level
• with tape measure and level

If you say:

• Met een rolmaat en een waterpas controleerde hij de plank

that is also correct, but it sounds a bit more explicit and less compact.

So the version without articles is natural and idiomatic.

Yes. Met covers both nouns.

So:

• Met rolmaat en waterpas = with a tape measure and a spirit level

Dutch often does this with coordinated nouns, just like English:

• with knife and fork
• met mes en vork

You do not need to repeat met before the second noun.

Usually not. In Dutch, controleren very often means to check, inspect, or verify.

So in this sentence, controleerde hij de plank most naturally means:

• he checked the board/plank

This is a common false friend for English speakers, because to control in English is usually more like beheersen or onder controle hebben in Dutch, depending on the context.

So here:

• controleren = check / inspect
• not usually control

It is the simple past tense of controleren.

Breakdown:

• infinitive: controleren
• stem: controleer
• past tense: controleerde

This is a regular weak verb. The ending is -de because the stem ends in a voiced sound, so it does not fall under the 't kofschip group that would take -te.

Examples:

• Ik controleer = I check
• Ik controleerde = I checked
• Hij controleerde = he checked

Also note that in the singular and plural simple past, weak verbs often look the same except for the subject:

• hij controleerde
• wij controleerden

Rolmaat means tape measure.

It is a compound noun, and Dutch writes compounds as one word. That is very common in Dutch.

So:

• rolmaat = rol
  • maat
• meaning: tape measure

A learner should get used to Dutch compounds like:

• waterpas
• gereedschapskist
• slaapkamerdeur

Even when English uses multiple words, Dutch often uses one.

Here, waterpas means spirit level or level, the tool used to check whether something is horizontal or vertical.

It can also appear in Dutch in other ways, for example as an adjective or adverb meaning level:

• Het hangt waterpas. = It hangs level.

But in your sentence, it is clearly a noun: a tool used together with the rolmaat.

Because plank is a de-word.

So:

• de plank = the plank / the board / the shelf

There is no special rule here that you can easily predict from meaning alone; you simply need to learn the noun with its article.

Good habit:

• learn plank as de plank
• not just plank

Depending on context, plank can mean:

• a plank
• a board
• a shelf

Putting that phrase first gives it emphasis. It highlights the method or tools used.

Compare:

• Hij controleerde de plank met rolmaat en waterpas.
  Neutral: he checked the plank with those tools.

• Met rolmaat en waterpas controleerde hij de plank.
  More emphasis on how he checked it.

Dutch is flexible about moving parts of the sentence to the first position, but when you do that in a main clause, the finite verb still has to stay in second position. That is why you get controleerde hij.

Yes, absolutely. That would be a very natural sentence too.

It is just a bit different in style:

• Met rolmaat en waterpas controleerde hij de plank.
  More compact, slightly more descriptive, with emphasis on the tools.

• Hij controleerde de plank met een rolmaat en een waterpas.
  More neutral and straightforward.

Both are correct. The choice depends on emphasis and style rather than grammar.