# Category: Geometry

## How Many Pennies did Otha Save?

Otha Anders used picking up pennies as a way to remember to pray.  In this 3-act activity we try to estimate how much he actually collected and stored in 5 gallon water jugs.  Kick off the activity with the article with…

## Hexadecimal colors or paint by number

Probably most of us have heard of and even used hexadecimal color codes. Don’t you wonder why their number descriptions really make sense? In this activity we first ask students to color in our Golden Spiral by giving them the…

## Rescue of the Chilean miners – The 33

On August 5, 2010, the San Jose copper-gold mine near Copiapó,Chile collapsed stranding 33 miners in a large cavern more than 2,000 feet below ground. A new movie has just been released about the incident, The 33. All of the…

## Glowing rectangles

People spend lots of time staring at their screens (glowing rectangles).  Kids spend hours each day using their cell phones, computers, tablets, television and more.  Use that interest to motivate your student’s analysis of screen ratios and what proportions they…

## How much have doughnuts changed?

Part of the Smithsonian’s Sally L. Steinberg Collection of Doughnut Ephemera — Click on the image to see it larger. When you are working on volume in your class, you can use this activity for students who might like to find…

## How Many Donuts is That?

Act One:  Take a look at the picture.  What is the first question that comes to mind? How many donuts is that?  What information would be useful? Act Two: See pictures below. Your students can view all five pictures on…

## California water measurements – chains, links, and furlongs

Help your students understand what they are reading or hearing about the California drought.  Terms like acre-feet, chains, and furlongs are often used to describe the volume of the reservoirs.  Give your class a little practice and appreciation of the…

## McDonalds moves towards antibiotic-free chicken

Recently McDonald’s announced that by 2016 they will use only chicken raised without the antibiotics that are used in human medicine.  McDonald’s plans to join Chick-fil-A, Panera Bread, Chiptotle, and Whole Foods in the move towards removing antibiotics in the…

## Huge Key Lime pie

On a cold and snowy day in Boston, two chefs created a huge Key Lime pie to remind the frozen people of the Northeast how tasty and warm the Keys of Florida are. After you show this movie to your…

## A parametric heart … with love

Valentine’s Day is a good excuse to explore parametric equations. First students figure the coordinates of this figure using trigonometric unit triangles. Then they simplify and accelerate this task with either a graphing calculator or with online software like Desmos…

## Kilauea’s lava flow

The volcano, Kilauea, on the Big Island of Hawaii, has been active and erupting since 2008.  There are two lava flows at present and one is now approaching homes on the Big Island. This is another example of natural events…

## How large a TV should I get?

This is a great looking room, but do you see what is wrong with this picture? Whether you are in middle school or high school, someday you are going to be moving out and you might need to select the…

## MAVEN arrives at Mars

Recently the MAVEN spacecraft (Mars Atmosphere and Volatile Evolution Mission) that was launched on November  18, 2013 reached Mars and attained an elongated orbit around the planet.  How does someone figure out how to do that?

## Wheel of Theodorus

Bring a little art into your math class as you begin to use the Pythagorean theorem and your students first meet irrational numbers.