Educational worksheet on the respiratory system for learning about breathing and body functions.

Let’s solve this step by step.

We are given a fill-in-the-blank worksheet about the respiratory system. The goal is to use the word bank at the top to correctly complete each sentence.

First, let’s look at the word bank:

- lungs
- air sacs
- respiratory
- cough
- diaphragm
- breathe in
- oxygen
- exhale
- nose or mouth
- carbon dioxide
- bronchi
- trachea

Now, we’ll go through each blank one by one and pick the best word that fits based on what we know about how breathing works.

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Sentence 1:
“All animals need ______ to make energy. Your body can get this from food, but it also needs ______.”

→ Animals need oxygen to make energy (from cellular respiration).
→ They also need to get rid of waste — which is carbon dioxide.
Wait — actually, rereading: “Your body can get this from food” — “this” refers to energy? But then it says “but it also needs ___”. That second blank should be something else needed for energy production — which is oxygen.

Actually, let’s think again:
The first blank: “All animals need ______ to make energy.” → That’s oxygen.
Second blank: “Your body can get this from food, but it also needs ______.” → Wait, “this” might refer to energy? But you don’t get energy directly from food without oxygen. Hmm.

Actually, looking at standard biology:
Animals need oxygen to break down food and make energy. So maybe the first blank is “oxygen”, and the second blank is... wait, no — perhaps the sentence means: You get energy from food, but you also need oxygen to release that energy.

But let’s check the next part:
“Food is broken down into glucose during digestion. Glucose travels through your blood to all parts of the body. At the same time, your ______ bring oxygen into your bloodstream through a process called ______.”

Ah! Now it makes sense.

So back to Sentence 1:
“All animals need oxygen to make energy. Your body can get this [energy] from food, but it also needs oxygen.” → That seems redundant.

Wait — maybe the first blank is “energy”? No, because it says “need ___ to make energy”.

Actually, correct science: Animals need oxygen to make energy from food. So:

First blank: oxygen
Second blank: ??? Let’s read ahead.

Next sentence: “Food is broken down into glucose... Glucose travels... At the same time, your ______ bring oxygen into your bloodstream...”

That blank is likely lungs.

Then: “through a process called ______.” → That’s respiratory? No — the process is called breathing, but “respiratory” is an adjective. Wait — the word bank has “respiratory” — but that’s not a process name.

Wait — the process of bringing oxygen in is called inhalation or breathing in — and “breathe in” is in the word bank!

But let’s hold on. Maybe we should do this in order.

Let me rewrite the whole text with blanks numbered:

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Original text with blanks marked:

All animals need _1_ to make energy. Your body can get this from food, but it also needs _2_. Food is broken down into glucose during digestion. Glucose travels through your blood to all parts of the body. At the same time, your _3_ bring oxygen into your bloodstream through a process called _4_.

When you _5_, air enters the body through the _6_. It moves through the _7_ and then into the _8_. From there, air goes into smaller tubes called _9_. At the end of these tubes are tiny air sacs called _10_. This is where gas exchange happens — oxygen moves into the blood, and _11_ moves out of the blood into the air sacs. Then, when you _12_, the air leaves your body.

Your lungs work with another important muscle called the _13_. When you breathe in, the diaphragm contracts and flattens, making more space in your chest cavity so your lungs can expand. When you breathe out, the diaphragm relaxes and moves up, pushing air out of your lungs.

It’s important to keep your respiratory system clean so oxygen can move freely through your body. If something gets stuck in your throat or lungs, your body will try to remove it by making you _14_. Smoking damages your lungs and makes it harder to breathe. If you often feel like you’re not getting enough oxygen, see a doctor. You may have asthma or another condition.

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Now, let’s fill them one by one using the word bank.

Word bank:
lungs, air sacs, respiratory, cough, diaphragm, breathe in, oxygen, exhale, nose or mouth, carbon dioxide, bronchi, trachea

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Blank 1: “All animals need ___ to make energy.”
→ Answer: oxygen (because cells use oxygen to produce energy from glucose)

Blank 2: “Your body can get this from food, but it also needs ___.”
→ “This” refers to energy? But you get energy from food + oxygen. Actually, the sentence is a bit awkward. Perhaps it means: You get fuel (glucose) from food, but you also need oxygen to burn it. So Blank 2 should also be oxygen? But that would repeat.

Wait — maybe Blank 1 is “energy”? No — “need energy to make energy” doesn’t make sense.

Alternative interpretation: All animals need oxygen to make energy. Your body can get [the raw materials for energy] from food, but it also needs oxygen. Still repetitive.

Perhaps Blank 2 is meant to be “something else” — but logically, it’s still oxygen.

Looking at common worksheets, sometimes they say: “All animals need oxygen to make energy. Your body gets energy from food, but it also needs oxygen to release that energy.”

So I think both 1 and 2 are “oxygen” — but that seems odd. Wait — maybe Blank 1 is “food”? No.

Another thought: In some contexts, they say animals need “nutrients” from food and “oxygen” from air. But the word bank doesn’t have “nutrients”.

Let’s skip and come back.

Blank 3: “your ___ bring oxygen into your bloodstream” → Clearly lungs

Blank 4: “through a process called ___” → The process of taking in oxygen is breathing in or inhalation. Word bank has “breathe in” — but that’s a verb phrase. Also has “respiratory” — but that’s an adjective. Wait — the process is called “respiration”, but “respiratory” is listed. Maybe they mean “respiratory system”? But the blank is after “called”, so probably a noun.

Actually, the process of gas exchange is part of the respiratory system, but the act of bringing air in is “inhalation” or “breathing in”. Since “breathe in” is in the word bank, and it’s a verb, but here it’s used as a noun? Unlikely.

Wait — perhaps Blank 4 is “respiration”? But “respiratory” is given. Maybe it’s a trick.

Let’s look at later blanks.

Blank 5: “When you ___, air enters the body” → That’s breathe in

Blank 6: “through the ___” → nose or mouth

Blank 7: “moves through the ___” → After nose/mouth, air goes to trachea (windpipe)

Blank 8: “then into the ___” → Trachea splits into bronchi, which go to lungs. But “bronchi” is plural. The sentence says “into the ___” — could be “lungs”? But then it says “from there, air goes into smaller tubes called ___” — so Blank 8 should be bronchi? Wait, no.

Standard path:
Nose/mouth → pharynx → larynx → trachea → bronchi → bronchioles → alveoli (air sacs)

In the text:
“air enters through the _6_ [nose or mouth]. It moves through the _7_ [trachea] and then into the _8_ [bronchi? or lungs?]”

Then: “From there, air goes into smaller tubes called _9_ [bronchioles? but word bank has “bronchi” — wait, “bronchi” are the larger tubes, then smaller ones are bronchioles, but word bank only has “bronchi” and “air sacs”.

Word bank: bronchi, air sacs

So likely:

Blank 7: trachea
Blank 8: bronchi
Blank 9: ? But word bank doesn’t have bronchioles. Oh — perhaps they consider “bronchi” as the main tubes, and then “smaller tubes” are not named, but the next is “air sacs”.

Text: “From there, air goes into smaller tubes called _9_. At the end of these tubes are tiny air sacs called _10_.”

But word bank has “bronchi” and “air sacs”. “Bronchi” are not smaller tubes — they are the main branches. Smaller tubes are bronchioles, but not in word bank.

Perhaps Blank 9 is not filled? Or maybe they misuse terms.

Another possibility: Sometimes “bronchi” is used loosely. But let’s see.

Perhaps Blank 8 is “lungs”, and Blank 9 is “bronchi”, but that doesn’t fit because bronchi are before the air sacs.

Standard: trachea → left and right bronchi → bronchioles → alveoli (air sacs)

Since “bronchioles” isn’t in word bank, and “bronchi” is, perhaps Blank 9 is “bronchi” — but that would be incorrect because bronchi are larger.

Wait — the text says: “moves through the _7_ and then into the _8_. From there, air goes into smaller tubes called _9_.”

If _7_ is trachea, _8_ could be bronchi, and _9_ could be... but no word for bronchioles. Unless they expect “bronchi” for _9_, but that doesn't make sense.

Perhaps _8_ is "lungs", and _9_ is "bronchi" — but bronchi are inside the lungs, and they are not smaller than the entry point.

I think there's a mistake in my reasoning.

Let me check online or recall standard elementary level.

In many simplified versions:

Air enters through nose/mouth → down trachea → into bronchi (which are in the lungs) → then to air sacs.

And they might call the bronchi the "tubes" leading to air sacs.

But the text says: "into the _8_. From there, air goes into smaller tubes called _9_."

So if _8_ is "bronchi", then _9_ should be something smaller, but not in word bank.

Unless _9_ is not needed, but it is.

Another idea: Perhaps "bronchi" is for _9_, and _8_ is "lungs".

Let's try that.

Blank 6: nose or mouth
Blank 7: trachea
Blank 8: lungs
Blank 9: bronchi — but bronchi are not smaller tubes; they are the main tubes entering the lungs.

This is confusing.

Perhaps in this context, "bronchi" is considered the smaller tubes after the trachea.

Let's look at the word bank again: we have "bronchi" and "air sacs", and "trachea".

Also, "respiratory" is there, but that's an adjective.

For Blank 4: "process called ___" — perhaps "respiration", but "respiratory" is given. Maybe they mean "the respiratory process", but it's awkward.

Another thought: In some curricula, they say the process is called "breathing", and "breathe in" is for inhalation.

Let's list all blanks and assign based on logic.

Blank 1: oxygen (animals need oxygen to make energy)
Blank 2: ? Let's say "oxygen" again, but that's duplicate. Perhaps "food" is implied, but not in bank. Wait, the sentence is: "Your body can get this from food" — "this" is energy, so you get energy from food, but you also need oxygen to convert it. So Blank 2 should be "oxygen". So both 1 and 2 are "oxygen"? That seems poor writing, but possible.

Perhaps Blank 1 is "energy", but "need energy to make energy" is circular.

I think it's a typo or poor phrasing, but in context, Blank 1 is "oxygen", Blank 2 is also "oxygen" — but let's see if there's another way.

Later in the text, it says "oxygen moves into the blood, and _11_ moves out" — that's carbon dioxide.

So for Blank 2, perhaps it's "carbon dioxide"? But that doesn't make sense because you don't need carbon dioxide to make energy; you produce it.

No.

Let's move to other blanks and come back.

Blank 3: lungs (bring oxygen into bloodstream)
Blank 4: ? Process called — perhaps "respiration", but "respiratory" is in bank. Maybe they want "respiratory" as in "respiratory system", but the blank is "called ___", so likely a noun. Perhaps "breathing", but not in bank. "Breathe in" is a verb.

Another idea: In some contexts, the process is called "gas exchange", but not in bank.

Perhaps Blank 4 is "respiration", and "respiratory" is a distractor, but we have to use the words given.

Let's count the blanks and words.

There are 14 blanks, and 12 words in the bank? Let's list the word bank size.

Word bank: 12 items: lungs, air sacs, respiratory, cough, diaphragm, breathe in, oxygen, exhale, nose or mouth, carbon dioxide, bronchi, trachea

Blanks: 14? Let's count from the text.

From earlier numbering: 1 to 14.

But "nose or mouth" is one item, even though it's two words.

Similarly, "breathe in" is one item.

So 12 items for 14 blanks? That can't be.

Perhaps I miscounted blanks.

Let me copy the text and count underscores.

"All animals need ______ to make energy. Your body can get this from food, but it also needs ______. Food is broken down into glucose during digestion. Glucose travels through your blood to all parts of the body. At the same time, your ______ bring oxygen into your bloodstream through a process called ______.

When you ______, air enters the body through the ______. It moves through the ______ and then into the ______. From there, air goes into smaller tubes called ______. At the end of these tubes are tiny air sacs called ______. This is where gas exchange happens — oxygen moves into the blood, and ______ moves out of the blood into the air sacs. Then, when you ______, the air leaves your body.

Your lungs work with another important muscle called the ______. When you breathe in, the diaphragm contracts and flattens, making more space in your chest cavity so your lungs can expand. When you breathe out, the diaphragm relaxes and moves up, pushing air out of your lungs.

It’s important to keep your respiratory system clean so oxygen can move freely through your body. If something gets stuck in your throat or lungs, your body will try to remove it by making you ______. Smoking damages your lungs and makes it harder to breathe. If you often feel like you’re not getting enough oxygen, see a doctor. You may have asthma or another condition."

Now, let's count the blanks:

1. need ______ to make energy
2. also needs ______
3. your ______ bring oxygen
4. process called ______
5. When you ______, air enters
6. through the ______
7. through the ______
8. into the ______
9. called ______
10. called ______
11. and ______ moves out
12. when you ______, the air leaves
13. called the ______
14. making you ______

Yes, 14 blanks.

Word bank has 12 items. But "nose or mouth" is one item, "breathe in" is one, etc.

List of word bank items:
1. lungs
2. air sacs
3. respiratory
4. cough
5. diaphragm
6. breathe in
7. oxygen
8. exhale
9. nose or mouth
10. carbon dioxide
11. bronchi
12. trachea

12 items for 14 blanks. That means some words are used twice, or I have a mistake.

Perhaps "respiratory" is not used, or something.

Another possibility: "respiratory" is for Blank 4, as "respiratory process", but it's adjective.

Or perhaps for Blank 4, it's "breathing", but not in bank.

Let's assume that "breathe in" and "exhale" are for the actions, and "respiratory" might be for the system, but in Blank 4, it's "process called", so likely not.

Perhaps Blank 4 is "respiration", and "respiratory" is a red herring, but we have to use the given words.

Let's look for clues in the text.

In the last paragraph, it says "keep your respiratory system clean" — so "respiratory" is used as an adjective, not for a blank.

So probably not used in blanks.

Then we have 11 useful words for 14 blanks? No, 12 words, but "respiratory" might not be used.

Perhaps "oxygen" is used twice.

Let's start filling with confidence.

Blank 5: "When you ______, air enters the body" → breathe in

Blank 6: "through the ______" → nose or mouth

Blank 7: "moves through the ______" → trachea (windpipe)

Blank 8: "then into the ______" → bronchi (the two main branches)

Blank 9: "smaller tubes called ______" → but word bank has no "bronchioles". Perhaps they mean "bronchi" for this, but that's not accurate. Or maybe "air sacs" is for 10, so 9 must be something else.

Another idea: In some simplifications, they say air goes to "bronchi" then to "air sacs", skipping bronchioles. So perhaps Blank 9 is not there, but it is.

Text: "From there, air goes into smaller tubes called ______. At the end of these tubes are tiny air sacs called ______."

So "smaller tubes" are likely bronchioles, but not in bank. Perhaps they expect "bronchi" for Blank 8, and for Blank 9, it's not specified, but we have to choose from bank.

Perhaps "bronchi" is for Blank 9, and Blank 8 is "lungs".

Let's try that.

Blank 8: lungs
Blank 9: bronchi — but bronchi are not smaller tubes; they are the tubes that enter the lungs.

This is problematic.

Perhaps "bronchi" is the answer for Blank 9, and Blank 8 is "trachea" but Blank 7 is already trachea.

Blank 7 is "moves through the ______" after nose/mouth, so trachea.

Then "into the ______" — could be "bronchi", then "from there, into smaller tubes" — but no word for that.

Unless "air sacs" is for 10, and 9 is left, but we have to fill.

Another thought: Perhaps "respiratory" is for Blank 4, and we accept it as "respiratory process".

Let's look at Blank 11: "and ______ moves out" — clearly carbon dioxide

Blank 12: "when you ______, the air leaves" → exhale

Blank 13: "muscle called the ______" → diaphragm

Blank 14: "making you ______" → cough

Blank 3: "your ______ bring oxygen" → lungs

Blank 1: "need ______ to make energy" → oxygen

Blank 2: "also needs ______" — perhaps "oxygen" again, or maybe "food", but not in bank. Or "carbon dioxide", but that doesn't make sense.

Perhaps Blank 2 is "energy", but not in bank.

Let's calculate how many times "oxygen" is used.

In the text, "oxygen" appears in the description, so likely used in blanks.

Perhaps for Blank 2, it's "oxygen", and for Blank 1, it's also "oxygen", but that's fine.

Then Blank 4: "process called ______" — what is left? We have "respiratory" unused.

Perhaps they mean "the respiratory process", so "respiratory" for Blank 4.

In some educational materials, they say "respiratory process".

So let's assume that.

Then for Blank 9: "smaller tubes called ______" — what is left? We have "air sacs" for 10, "bronchi" for 8 or 9.

Let's list assigned so far:

Blank 1: oxygen
Blank 2: oxygen (assume)
Blank 3: lungs
Blank 4: respiratory (as in respiratory process)
Blank 5: breathe in
Blank 6: nose or mouth
Blank 7: trachea
Blank 8: ?
Blank 9: ?
Blank 10: air sacs
Blank 11: carbon dioxide
Blank 12: exhale
Blank 13: diaphragm
Blank 14: cough

Left words: bronchi

Only "bronchi" left, but two blanks: 8 and 9.

That can't be.

Perhaps Blank 8 is "bronchi", and Blank 9 is not filled, but it is.

Another idea: Perhaps "bronchi" is for Blank 9, and Blank 8 is "lungs", and "smaller tubes" is a misnomer, or in their curriculum, bronchi are considered the tubes leading to air sacs.

In many elementary texts, they say: air goes to bronchi, then to air sacs, omitting bronchioles.

So perhaps Blank 8: lungs (air enters the lungs)
Blank 9: bronchi (smaller tubes within lungs)

But bronchi are not smaller; they are the main tubes.

Perhaps Blank 8: bronchi, Blank 9: air sacs, but then "at the end of these tubes are air sacs" — if "these tubes" are bronchi, then air sacs are at the end, which is approximately true.

And "smaller tubes" might be a mistake, or they consider bronchi as the tubes.

So let's try:

Blank 8: bronchi
Blank 9: air sacs? But then Blank 10 is "called ______" for air sacs, so conflict.

Text: "into the ______. From there, air goes into smaller tubes called ______. At the end of these tubes are tiny air sacs called ______."

So three things: into A, then into smaller tubes B, then at end of B are air sacs C.

So A, B, C are different.

A could be lungs, B could be bronchi, C air sacs — but bronchi are not smaller than lungs; lungs contain bronchi.

Perhaps A is trachea, but Blank 7 is trachea.

Blank 7 is "moves through the ______" which is trachea, then "into the ______" which should be bronchi, then "from there, into smaller tubes" — which should be bronchioles, but not in bank.

I think there's an error in the worksheet or my understanding.

Perhaps "bronchi" is for Blank 9, and Blank 8 is "lungs", and "smaller tubes" refers to bronchi within the lungs.

In that case, Blank 8: lungs
Blank 9: bronchi
Blank 10: air sacs

Then "at the end of these tubes [bronchi] are air sacs" — which is roughly correct, as bronchi branch to bronchioles to alveoli.

So for elementary level, it might be acceptable.

Then we have used "bronchi" for 9.

Now, what about Blank 4? We have "respiratory" left, and no other words.

Words used:
1. oxygen
2. oxygen (again)
3. lungs
4. ?
5. breathe in
6. nose or mouth
7. trachea
8. lungs? But "lungs" is already used for 3.

Problem: "lungs" can't be used twice unless allowed.

Word bank has "lungs" once, so probably not reused.

So Blank 3: lungs
Blank 8: cannot be lungs.

So Blank 8 must be "bronchi"

Then Blank 9: what? Only "air sacs" left for 10, so 9 must be something else.

Perhaps "respiratory" for 9, but that doesn't make sense.

Another possibility: "respiratory" for Blank 4, and for Blank 9, it's not filled, but we have to.

Let's list all words and see which are not used yet.

Assume:

Blank 1: oxygen
Blank 2: carbon dioxide? But that doesn't make sense for "needs".

Perhaps Blank 2 is "food", but not in bank.

I recall that in some versions, the sentence is: "All animals need oxygen to make energy. Your body can get energy from food, but it also needs oxygen." So Blank 1: oxygen, Blank 2: oxygen.

Then for Blank 4: "process called respiration" — but "respiratory" is given, so perhaps they want "respiratory" as a noun, which is rare.

Perhaps "breathe in" for Blank 4, but that doesn't fit.

Let's look at the very beginning: "Use the words in the box to fill in the blanks. Type the words in as often as needed."

Oh! I missed that! "Type the words in as often as needed." So words can be used multiple times.

That solves it!

So "oxygen" can be used for Blank 1 and 2.

"lungs" can be used for Blank 3 and possibly others, but likely not.

"breathe in" for 5, "exhale" for 12, etc.

So let's proceed.

Blank 1: oxygen
Blank 2: oxygen (since you need oxygen to make energy from food)
Blank 3: lungs
Blank 4: ? Still problem.

With reuse allowed, we can use "respiratory" for Blank 4, as "respiratory process".

Or perhaps "breathing", but not in bank.

Another idea: In some contexts, the process is called "ventilation", but not in bank.

Perhaps "gas exchange", but not.

Let's see what is left.

After assigning obvious ones:

Blank 5: breathe in
Blank 6: nose or mouth
Blank 7: trachea
Blank 8: bronchi (air enters the bronchi after trachea)
Blank 9: ? smaller tubes — perhaps "bronchi" again, but that doesn't make sense. Or "air sacs" for 10, so 9 must be something.

Perhaps "respiratory" for 9, but no.

Another thought: "bronchi" are the tubes, and "air sacs" are at the end, so perhaps Blank 9 is not "smaller tubes" but the text says "smaller tubes called", so likely bronchioles, but not in bank.

Perhaps in this worksheet, "bronchi" is for the smaller tubes, and Blank 8 is "lungs".

Let's set:

Blank 8: lungs
Blank 9: bronchi (considered the smaller tubes within lungs)
Blank 10: air sacs

Then "at the end of these tubes [bronchi] are air sacs" — acceptable for elementary level.

Then Blank 4: "process called ______" — what to put? We have "respiratory" left, and "cough" for 14, "diaphragm" for 13, "carbon dioxide" for 11, "exhale" for 12.

So for Blank 4, "respiratory" is the only choice, so we'll use it as "respiratory process".

Perhaps it's "respiration", but "respiratory" is given, so ok.

So let's finalize:

Blank 1: oxygen
Blank 2: oxygen
Blank 3: lungs
Blank 4: respiratory
Blank 5: breathe in
Blank 6: nose or mouth
Blank 7: trachea
Blank 8: lungs — but "lungs" is already used for 3, and we can reuse, so ok.
Blank 9: bronchi
Blank 10: air sacs
Blank 11: carbon dioxide
Blank 12: exhale
Blank 13: diaphragm
Blank 14: cough

But Blank 8: "into the lungs" — then "from there, air goes into smaller tubes called bronchi" — but bronchi are the tubes that bring air into the lungs, so if air is already in the lungs, going into bronchi doesn't make sense.

Typically, air goes: trachea -> bronchi -> lungs (specifically, to the air sacs in the lungs).

So better:

Blank 7: trachea
Blank 8: bronchi
Blank 9: ? still problem.

Perhaps Blank 9 is "bronchioles", but not in bank.

I think the intended answer is:

Blank 8: bronchi
Blank 9: air sacs — but then Blank 10 is "called air sacs", so conflict.

Text: "into the ______. From there, air goes into smaller tubes called ______. At the end of these tubes are tiny air sacs called ______."

So if Blank 8: bronchi, then "from there" (from bronchi) into smaller tubes — which should be bronchioles, but not in bank, so perhaps they expect "air sacs" for Blank 9, but then Blank 10 is also air sacs.

That doesn't work.

Unless "smaller tubes" is a mistake, and it's "directly to air sacs".

In that case, Blank 9: air sacs, but then Blank 10 is "called air sacs", so duplicate.

Perhaps Blank 9 is not there, but it is.

Another idea: "respiratory" for Blank 9, but that doesn't make sense.

Let's search for similar worksheets online in my mind.

I recall that in some, they have:

- air enters through nose/mouth
- down trachea
- into bronchi
- then to bronchioles
- then to alveoli (air sacs)

But since "bronchioles" not in bank, perhaps for this worksheet, "bronchi" is for the smaller tubes, and Blank 8 is "lungs".

And "respiratory" for Blank 4.

So I'll go with that.

Final assignment:

1. oxygen
2. oxygen
3. lungs
4. respiratory
5. breathe in
6. nose or mouth
7. trachea
8. lungs (reused)
9. bronchi
10. air sacs
11. carbon dioxide
12. exhale
13. diaphragm
14. cough

For Blank 8: "into the lungs" — then "from there, air goes into smaller tubes called bronchi" — which is backwards, but perhaps in their model, lungs contain the bronchi as smaller tubes.

To make it logical, perhaps Blank 8: bronchi, and Blank 9: air sacs, and ignore "smaller tubes" or consider air sacs as the tubes, but air sacs are sacs, not tubes.

I think the best is to put:

Blank 8: bronchi
Blank 9: air sacs — and assume "smaller tubes" is a misnomer, or in their context, air sacs are considered tubes.

But the text says "smaller tubes called ______. At the end of these tubes are tiny air sacs" — so "these tubes" are not air sacs; air sacs are at the end.

So Blank 9 must be the tubes, Blank 10 air sacs.

So Blank 9: bronchi (even though not smaller), Blank 10: air sacs.

Then "at the end of these tubes [bronchi] are air sacs" — which is approximately true.

So:

Blank 8: ? After trachea, into bronchi, so Blank 8: bronchi
Then "from there" (from bronchi) into smaller tubes — but no word, so perhaps Blank 9 is not filled, but we have to.

Perhaps "respiratory" for Blank 9, but that doesn't make sense.

I think I found a solution: in some worksheets, "bronchi" is for the main tubes, and "bronchioles" is not mentioned, so perhaps Blank 9 is omitted, but it's there.

Another possibility: "trachea" for Blank 7, "bronchi" for Blank 8, and for Blank 9, "air sacs" , but then Blank 10 is also air sacs.

No.

Let's count the words again.

Perhaps "breathe in" is for Blank 5, "exhale" for 12, "cough" for 14, "diaphragm" for 13, "carbon dioxide" for 11, "air sacs" for 10, "bronchi" for 9, "trachea" for 7, "nose or mouth" for 6, "lungs" for 3, "oxygen" for 1 and 2, and for Blank 4 and 8, what is left? "respiratory" and perhaps "lungs" again.

For Blank 8: "into the lungs" — so "lungs" for 8.

Then Blank 4: "respiratory"

And for Blank 9: "bronchi" — but then "from there [lungs] into smaller tubes called bronchi" — which is wrong because bronchi are before lungs.

Unless "lungs" here means the organ, and bronchi are inside.

In anatomy, the bronchi are part of the lungs, so when air enters the lungs, it goes to the bronchi.

So: after trachea, air enters the lungs (Blank 8: lungs), then within the lungs, it goes into smaller tubes called bronchi (Blank 9: bronchi), then to air sacs (Blank 10: air sacs).

That could work for elementary level.

So I'll go with that.

So final answers:

1. oxygen
2. oxygen
3. lungs
4. respiratory
5. breathe in
6. nose or mouth
7. trachea
8. lungs
9. bronchi
10. air sacs
11. carbon dioxide
12. exhale
13. diaphragm
14. cough

Now, to write it out.

For the student, I'll provide the completed text with the words filled in.

Since the user asked to solve the problem, and it's a fill-in-the-blank, I'll list the answers in order.

But in the response, I need to provide the final answer as the completed sentences or the list.

Given the format, probably list the words for each blank.

But to be clear, I'll write the filled text.

However, the instruction is to provide the final answer after reasoning.

So for Final Answer, I'll list the words in order of the blanks.

So:

Final Answer:
1. oxygen
2. oxygen
3. lungs
4. respiratory
5. breathe in
6. nose or mouth
7. trachea
8. lungs
9. bronchi
10. air sacs
11. carbon dioxide
12. exhale
13. diaphragm
14. cough

But let's verify if "respiratory" for Blank 4 is acceptable. Upon second thought, in many sources, the process is called "respiration", and "respiratory" is the adjective for the system. But since "respiration" is not in the bank, and "respiratory" is, and the instruction is to use the words in the box, we have to use it.

Perhaps for Blank 4, it's "breathing", but not in bank.

Another idea: "breathe in" for Blank 4, but that doesn't fit because "process called breathe in" is grammatically incorrect; "breathe in" is a verb phrase.

Whereas "respiratory" can be used as "respiratory process".

So I think it's ok.

Some might argue that Blank 4 should be "gas exchange", but not in bank.

So I'll stick with this.

For the student, I'll explain simply.

But since ExplainAnswer is false, I won't explain, just provide final answer.

The user options are all false, so only Final Answer section.

So in the response, only Final Answer with the list.

But to be precise, let's box the answers.

Since it's a fill-in, perhaps write the completed text, but that might be long.

Given the format, listing the words for each blank is fine.

So: