Blog

Short posts about the things our tools are for. Each one lists its sources and the date we checked them.

• 2027 US Federal Holidays and Long Weekends
  Every US federal holiday in 2027 with its weekday, which ones make a three-day weekend, and what an observed date means.
• When Should Kids Know Their Multiplication Facts?
  What the Common Core says about multiplication facts by Grade 3, how many facts there really are, and what the 2024 NAEP Grade 4 math results do and do not show.
• Where Sudoku Came From
  The short history of sudoku: an American puzzle called Number Place in 1979, a Japanese publisher that named it, and the newspaper craze of 2004 and 2005.
• Do Sudoku and Crosswords Protect Your Brain?
  A 15-year Scottish study followed nearly 500 people. It found that puzzle-style mental activity went with higher ability later in life, but did not change how fast ability declined.
• Handwriting vs Typing: What a 2024 Brain Study Found
  A 2024 EEG study found more brain connectivity when students wrote by hand than when they typed. Here is what was tested, and why it does not prove kids learn better by hand.
• Why Leap Years Exist
  A solar year is not a whole number of days. Here is the leap year rule, why the calendar was reformed in 1582, and which upcoming years are leap years.
• What Is an ISO Week Number?
  Calendars with week numbers follow ISO 8601: weeks start on Monday and week 1 is the one containing January 4. Why January 1 can belong to the old year.
• How Many Sudoku Grids Are There?
  There are about 6.67 sextillion completed sudoku grids, and the smallest number of clues that can give a single solution is 17. A look at the numbers.
• How to Solve Sudoku Without Guessing
  Learn the two basic sudoku techniques, scanning for hidden singles and filling in naked singles, with small examples. Easy and medium puzzles need nothing else.
• Wide Ruled vs College Ruled Paper
  Wide ruled paper has lines 11/32 inch (8.7 mm) apart, college ruled 9/32 inch (7.1 mm), narrow ruled 1/4 inch (6.4 mm). When to use each, and a bit of history.
• Who Invented the Word Search?
  Norman Gibat published a word search in the Selenby Digest in Norman, Oklahoma on March 1, 1968. Earlier claims exist too. A short history of the puzzle.
• Maze vs Labyrinth
  In everyday speech the words mean the same thing, but a labyrinth can also mean a single winding path with no choices. How the two terms are used.
• The History of Bingo
  Bingo traces back to an Italian lotto game from about 1530, a French card design in 1778, and a carnival game called Beano that Edwin Lowe brought to New York in 1929.
• How Long Does It Take to Form a Habit?
  The famous 66 days comes from a 2009 study of 96 people. It was a median in a range from 18 to 254 days, and it is not a rule. What the research says.
• Why Flash Cards Work
  A large review of ten study techniques rated practice testing and spreading study over time as the most useful, and rereading and highlighting as the least.
• Types of Graph Paper and a Short History
  From quad paper to isometric and dot grid: the common kinds of graph paper, their grid spacings, and the 1794 patent behind the first commercial coordinate paper.
• The Checklist That Cut ICU Infections
  In 2006 a program in Michigan ICUs used a short checklist for central line insertion. Infection rates fell sharply. What the study did and did not prove.
• Patterns in the Multiplication Table
  The multiplication table is full of patterns that make facts easier to remember. The digits of the 9s always add up to 9, and more tricks that you can check yourself.
• Cross Stitch Fabric Count Explained
  What 14-count Aida means, how to turn a stitch count into inches, why 2 over 2 on 28-count equals 14-count, and a short history of the craft.
• What NIST Says About Passwords
  NIST's password guidance (SP 800-63B) recommends long passwords, no forced complexity rules, no routine changes, and checking against breached lists. A plain summary.
• Color Contrast Ratios Explained
  WCAG level AA asks for a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text. What counts as large text, and the exceptions.
• Color Blindness and Design
  About 1 in 12 men have a color vision deficiency, most often red-green. What that means when you pick colors for charts, signs and printouts.
• US Letter vs A4
  Letter is 8.5 x 11 inches and A4 is 210 x 297 mm. Where each is used, why A4 halves neatly, and what to check when you print a PDF.
• A Short History of the Bookmark
  The oldest known bookmark is a 6th-century leather piece found in Egypt. How bookmarks moved from cords and parchment strips to woven silk and printed card.
• What to Put on a Certificate
  A good certificate has a clear title, a name, a reason, a date and a signature. Wording ideas for achievement, completion and participation certificates.