Printable worksheet designed to reinforce basic geometry vocabulary through definition completion.

Let’s go through each term one by one and fill in the blanks with the correct geometry vocabulary.

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1) Point
A point is a location in space. It has no size, so we represent it with a dot and label it with a capital letter.
→ So: “Point is a location in space that is represented by a dot with a capital letter.”

But looking at the structure of the sentence:
“Point _______ in space that is _______ with a _______ letter.”
The most standard definition is:
“Point is a location in space that is named with a capital letter.”

✔ Final for #1:
Point is a location in space that is named with a capital letter.

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2) Line
A line is made up of points that go on forever in two directions. It never ends.
So: “Line — series of points that extend in two opposite directions without end.”

✔ Final for #2:
Line — series of points that extend in two opposite directions without end.

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3) Segment
A segment is part of a line between two endpoints. It includes those two points and all the points between them.
So: “Segment — two endpoints and all the points on the line between the endpoints.”

Wait — actually, more precisely: “two points (called endpoints)” — but the blank says “two ___”, then “on the ___ between”.

Standard definition: A segment consists of two endpoints and all the points between them on the line connecting them.

So: “Segment — two endpoints and all the points on the segment between the endpoints.” → That’s circular.

Better: “Segment — two points and all the points on the line between the endpoints.” But “endpoints” are already mentioned.

Actually, common phrasing: “A segment is defined by two endpoints and includes all points between them.”

Looking at the sentence:
“Segment _______ two _______ and all the points on the _______ between the endpoints.”

First blank: probably “consists of” or “is”. Let’s assume “is”.

Then: “two endpoints” — yes.

Then: “on the line” — because the segment lies on a line.

✔ Final for #3:
Segment is two endpoints and all the points on the line between the endpoints.

*(Note: Some might say “on the segment”, but that’s redundant. “On the line” is correct geometrically.)*

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4) Ray
A ray starts at one endpoint and goes infinitely in one direction.
So: “Ray — one endpoint and all the points of a line on one side of the endpoint.”

Or sometimes “direction”, but “side” is fine.

✔ Final for #4:
Ray — one endpoint and all the points of a line on one side of the endpoint.

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5) Collinear Points
Collinear means lying on the same straight line.
So: “Points that if connected, form a straight line.”
But better: “Points that lie on the same line.”

Sentence: “Points that if __________, form a __________ line.”

Common phrasing: “Points that, when connected, form a straight line.” But technically, any two points form a straight line — collinear means three or more points lie on the same line.

But for this level: “Points that if joined, form a straight line.” Or “lie on”.

Actually, standard definition: “Collinear points are points that lie on the same line.”

So perhaps: “Points that if placed together, form a single straight line.” Hmm.

Looking at the sentence structure:
“Points that if __________, form a __________ line.”

Best fit: “Points that if connected, form a straight line.” — even though it’s not perfectly precise, it’s acceptable for middle school.

Alternatively: “Points that lie on the same line.” But the sentence forces “if ___ , form a ___ line.”

Another option: “Points that if aligned, form a straight line.”

I think “connected” is safest.

✔ Final for #5:
Points that if connected, form a straight line.

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6) Non-Collinear Points
These are points that do NOT lie on the same line. If you connect them, they don’t make a straight line — they make a shape like a triangle.

Sentence: “Points that if connected do __________ form a straight __________.”

So: “do not form a straight line.”

✔ Final for #6:
Points that if connected do not form a straight line.

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7) Plane
A plane is a flat surface that extends infinitely in all directions. It’s 2-dimensional.

Sentence: “Plane — flat __________ dimensional surface.”

Answer: two

✔ Final for #7:
Plane — flat two dimensional surface.

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Now let’s compile all answers neatly:

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Final Answer:
1) Point is a location in space that is named with a capital letter.
2) Line — series of points that extend in two opposite directions without end.
3) Segment is two endpoints and all the points on the line between the endpoints.
4) Ray — one endpoint and all the points of a line on one side of the endpoint.
5) Collinear Points — Points that if connected, form a straight line.
6) Non-Collinear Points — Points that if connected do not form a straight line.
7) Plane — flat two dimensional surface.