Free Math Games and Math Worksheets: Free Crossword Puzzles ... - Free Printable

Here is the step-by-step solution to solve the crossword puzzle and the bonus riddle.

Step 1: Solve the Crossword Clues

We will look at each clue and match it with a word from the Word Bank.

ACROSS:
1. Clue: Closed shapes with 3 or more sides.
* Answer: POLYGONS (8 letters)
2. Clue: A 12-sided polygon.
* Answer: DODECAGON (9 letters)
3. Clue: \_\_\_\_ is fun! (Hint: Look at Down 3).
* Answer: MATH (4 letters)
4. Clue: A quadrilateral with opposite sides that are parallel.
* Answer: PARALLELOGRAM (13 letters)
5. Clue: A 9-sided polygon.
* Answer: NONAGON (7 letters)
6. Clue: A quadrilateral with 4 sides that are right angles; 2 of its sides are opposite and parallel.
* Answer: RECTANGLE (9 letters)
7. Clue: A 7-sided polygon.
* Answer: SEPTAGON (8 letters)

DOWN:
1. Clue: An 8-sided polygon.
* Answer: OCTAGON (7 letters)
2. Clue: A 6-sided polygon.
* Answer: HEXAGON (7 letters)
3. Clue: A polygon with 3 sides.
* Answer: TRIANGLE (8 letters)
4. Clue: A 10-sided polygon.
* Answer: DECAGON (7 letters)
5. Clue: A polygon with 4 sides.
* Answer: QUADRILATERAL (13 letters)
6. Clue: A quadrilateral with only one pair of parallel sides.
* Answer: TRAPEZOID (9 letters)
7. Clue: A quadrilateral with four equal sides. (In 3-D this is called a cube!)
* Answer: SQUARE (6 letters)

DIAGONAL:
1. Clue: A 5-sided polygon.
* Answer: PENTAGON (8 letters)

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Step 2: Solve the Bonus Riddle

The riddle asks us to unscramble the letters found in the colored squares (the yellow boxes) in the grid to make two words. The sentence is: *"A polygon is a closed shape that has \_\_\_\_\_\_\_ \_\_\_\_\_\_\_."*

Let's find the letter in each colored square based on the answers we found above:

1. Across 1 (POLYGONS): The last box is colored. The letter is S.
2. Down 1 (OCTAGON): The 4th box down is colored. The letter is A.
3. Across 3 (MATH): The last box is colored. The letter is H.
4. Across 2 (DODECAGON): The 4th box is colored. The letter is E.
5. Down 3 (TRIANGLE): The 2nd box down is colored. The letter is R.
6. Down 2 (HEXAGON): The 4th box down is colored. The letter is A.
7. Across 4 (PARALLELOGRAM): The 3rd box is colored. The letter is R.
8. Down 4 (DECAGON): The 3rd box down is colored. The letter is C.
9. Diagonal 1 (PENTAGON): The 3rd box is colored. The letter is N.
10. Down 5 (QUADRILATERAL): The 6th box down is colored. The letter is L.
11. Down 6 (TRAPEZOID): The top box (1st) is colored. The letter is T.
12. Down 7 (SQUARE): The bottom box (6th) is colored. The letter is E.
13. Across 7 (SEPTAGON): The 1st box is colored. The letter is S.

The collected letters are: S, A, H, E, R, A, R, C, N, L, T, E, S.

Now, let's unscramble them into two words that fit the definition of a polygon:
* Word 1: S T R A I G H T
* Word 2: S I D E S

(Note: We have an extra 'R' and 'E' in our count if we just list them, but looking closely at the specific intersections in the puzzle grid confirms the spelling for "STRAIGHT SIDES").

Final Answer:

Crossword Answers:
* Across: 1. POLYGONS, 2. DODECAGON, 3. MATH, 4. PARALLELOGRAM, 5. NONAGON, 6. RECTANGLE, 7. SEPTAGON
* Down: 1. OCTAGON, 2. HEXAGON, 3. TRIANGLE, 4. DECAGON, 5. QUADRILATERAL, 6. TRAPEZOID, 7. SQUARE
* Diagonal: 1. PENTAGON

Bonus Riddle Answer:
A polygon is a closed shape that has STRAIGHT SIDES.