Ken's Puzzle of the Week

Third Grade Puzzles

I visited my son's class this year and shared various puzzles every other week.  Here's a compilation of some of their favorites.  Most will be familiar to the readers of this site already, but I enjoyed revisiting some of these, so perhaps you will, too.  No need to send solutions.  A DOC file with solutions is provided.

1. Mini-Sudoku – Place 1-3 in each row and column

2. OTTFFSS.  What letter comes next?
3. Fifteen toothpicks in three squares, remove 6 to leave ten.

4. 9 dots (3x3). Connect them with 4 straight lines without lifting your pencil.

5. 16 dots (4x4).  Connect them with 6 straight lines, ending where you begin.
6. You have a 3 and 5 gallon container.  How can you make exactly 4 gallons?
7. Magic Square.  Place 1-9 into a 3x3 grid such that every row, column and diagonal sum to 15.
8. Why is this a Christmas greeting? ABCDEFGHIJKMNOPQRSTUVWXYZ
9. Persistence Numbers: Take a 2 digit number and multiply its digits. Repeat until you reach a single digit.  What starting number requires the most steps?
10. How many squares (of any size) are on a checkerboard?
11. What is the most money you can have (in coins) without having exactly $1?
12. What numbers come next? 1, 0, 3, 11, 15, ?
13. A bottle of soda costs $3.  The soda is worth $2 more than the bottle.  How much is the bottle worth?
14. There are 9 balls and one is slightly heavy.  Find it with only two weighings on a balance scale.
15. Man, Grain, Goat, and Wolf, crossing a river.  The man may take only one of his possessions on each trip.  How does he do it without the goat eating the grain or the wolf eating the goat?
16. A lily in a pond doubles its size every day.  It takes 2 weeks to cover the pond.  When is the pond half covered?
17. Place 8 queens on a chessboard, such that no queen attacks any other.
18. How many flowers do I have if all of them are roses except two, all of them are tulips except two, and all of them are daisies except two?  [Two answers.]
19. 3 hens can lay 3 eggs in 3 days.  How long will it take 6 hens to lay 6 eggs?
20. Place only 4 marks on a 12-inch ruler to be able to measure 1 to 12 inches.
21. Use six toothpicks to make four equilateral triangles.
22. deft, laughing, hijack, calmness, canopy, [?], stump.  What word could be [?]
23. Two days ago I was 29.  Next year I will be 32.  When is my birthday?
24. A clock’s hands are at a right angle how many times between noon and midnight?
25. A snail climbs up 3 feet every day and slips down 2 feet each night.  How long until he exits a 10 foot well?

Source: Various puzzle sources.  Here is a Word DOC file with puzzles and solutions.