That Common Misconception About Probability

Dependent vs Independent Events

A couple posts ago I began talking about probabilities. I want to spend some more time on the topic because it’s one of those concepts that can be obviously easy one minute…

The “ Zero Power Rule” Explained

lesson thirty-seven

Exponents seem pretty straightforward, right? Raise a number to the power of 1 means you have one of that number, raise to the power of 2 means you have two of the number multiplied together, power 3 means three…

Can You Solve This Intro Probability Problem?

lesson thirty-six

An urn contains 10 balls: 4 red and 6 blue. A second urn contains 16 red balls and an unknown number of blue balls. A single ball is drawn from each urn. The probability that both balls are the…

Prime Numbers & The Sieve of Eratosthenes

lesson thirty-four

When it comes to number envy, primes definitely steal the show, and for good reason. They’re fundamental, mysterious and hard to come by. They’re valuable for encryption and at the heart of some of…

lesson thirty-three

The Division Algorithm as Mental Math

mental math series, part 14

Did you know the division algorithm is already a mental math process?

Could You Pass New York’s Algebra I Exam?

Only 63% of NY Students Did This Year

Yesterday there was an interesting article in the New York Times discussing New York’s Regents Algebra I exam. This year the exam, which aligned with new standards, had…

What Do Fractional Exponents Mean?

lesson thirty-one

Fractions as exponents?! Don’t worry, it’s just notational shorthand for powers and roots. Once you understand it, they’re easy as pie!

lesson thirty

Strategies for Mentally Adding Number Lists

mental math series, part 13

Every once in a while you come across a list of numbers to add that leaves you reaching for your calculator. Today we’ll look at some…

Understanding Common Core Math Models

from elementary through high school, consistency is key

An Unusual Number Solution

lesson twenty-nine, part 2

Ready for the solution to Wilfred’s number problem???

Here’s the problem from last lesson:

Wilfred heard that there is only one whole number between 2 and 200…

Intro to Distance, Rate & Time Problems

lesson twenty-eight

This past weekend I visited my parents. I was on a stretch of highway about five miles from the edge of the small town where they live when I was passed by four cars in the space of a few minutes …