Tarkistakaa, että jokainen heijastin näkyy.

Tarkistakaa is the imperative form of the verb tarkistaa (to check, to inspect, to make sure).

Specifically, it is the 2nd person plural imperative, so it is used when speaking to:

• more than one person: Check...
• or one person politely: like a formal Please check...

So in this sentence, Tarkistakaa gives an instruction or command.

The ending -kaa / -kää is the usual marker for the 2nd person plural imperative in Finnish.

For example:

• tule = come! (to one person)
• tulkaa = come! (to several people / polite)

So:

• tarkista = check! (singular, informal)
• tarkistakaa = check! (plural or polite)

The vowel is -kaa here because of vowel harmony.

It can be either, depending on context.

Finnish uses the same form for:

• you all
• you in a polite/formal sense

So Tarkistakaa could mean:

• You all, check that...
• or Please check that... when addressing one person formally

Without context, both are possible.

Because Finnish often leaves out subject pronouns when the verb form already shows who the subject is.

In Tarkistakaa, the ending already tells you it is addressed to you plural / polite you, so te is unnecessary.

You could say:

• Te tarkistakaa, että...

but that usually sounds more emphatic, as if stressing you.

Että means that and introduces a subordinate clause.

So the structure is:

• Tarkistakaa = Check / Make sure
• että jokainen heijastin näkyy = that every reflector is visible

It connects the main instruction to what should be checked.

This is very similar to English:

• Check that every reflector is visible.

In Finnish, a comma is normally used before a subordinate clause introduced by words like että.

So:

• Tarkistakaa, että...

This is standard Finnish punctuation.

English is less strict about this kind of comma, but Finnish generally requires it.

Jokainen means each or every, and it focuses on items one by one.

So:

• jokainen heijastin = every reflector / each reflector

By contrast, kaikki means all:

• kaikki heijastimet = all the reflectors

Both can sometimes translate naturally into English, but the grammar is different:

• jokainen heijastin näkyy = every reflector is visible
• kaikki heijastimet näkyvät = all the reflectors are visible

Because jokainen is followed by a singular noun in Finnish.

So Finnish says:

• jokainen heijastin = literally each reflector

Even though the overall meaning is plural in English (every reflector), the Finnish grammar is singular.

That is why:

• the noun is singular: heijastin
• the verb is also singular: näkyy

Because the grammatical subject is jokainen heijastin, which is treated as singular.

So Finnish agrees with the singular idea of each/every one:

• jokainen heijastin näkyy = every reflector is visible

Compare:

• jokainen heijastin näkyy = singular verb
• kaikki heijastimet näkyvät = plural verb

This is one of the most important things to notice in this sentence.

Näkyy comes from the verb näkyä, which means:

• to be visible
• to be seen
• to show up

In this sentence, it means that the reflector can be seen clearly.

So heijastin näkyy means:

• the reflector is visible
• or literally the reflector can be seen

It is not the same as:

• katsoa = to look at
• näyttää = to show / to look like / to seem

Heijastin is in the nominative singular.

Here it is the subject of the verb näkyy, so nominative is the normal case:

• jokainen heijastin näkyy

If you learn the sentence as a pattern, it is:

• jokainen + singular nominative noun + singular verb

Examples:

• jokainen oppilas ymmärtää = every student understands
• jokainen ovi on auki = every door is open

Yes, Finnish word order is fairly flexible, but this version is the most neutral and natural.

Neutral order:

• Tarkistakaa, että jokainen heijastin näkyy.

You might see other orders for emphasis, but they would change the focus slightly. For a learner, the given word order is the best one to use.

Inside the subordinate clause, jokainen heijastin näkyy is the standard order:

• subject first
• verb after it

It can correspond to both, depending on context.

• Tarkistaa often means to check
• but in instructions like this, English may naturally use make sure

So possible natural translations are:

• Check that every reflector is visible.
• Make sure that every reflector is visible.

The Finnish grammar itself does not force only one of these.

Heijastin means reflector or, in some contexts, a reflective safety reflector.

In Finnish everyday life, heijastin often refers to the reflective item people wear or attach to clothing or bags so they are visible in the dark.

So the sentence sounds like a safety instruction: make sure each reflector can be seen.