Stroboscopic Effect vs Spirolaterals

Did you ever notice the wheels on the car driving next to you sometimes appear to be spinning backwards? This is referred to as the stroboscopic (or wagon-wheel) effect. It occurs when an object is rotated at certain speeds, making the object to appear to stop or even go backwards. Rotate 4 different objects in either direction (clockwise or counterclockwise). You can increase the speed until you see it appear to stop or reverse. On one of the objects, a wheel with different colored alternating rings, you can make it appear as if the rings of this single option are turning in opposite directions. Universal App - supports native iPad, iPhone and iPhone 4's Retina display. WARNING - Those with Epilepsy or those subject to seizures are usually cautioned to avoid strobe lights or similar effects.

Spirolaterals allows you to explore geometric line designs based on applying a simple rule to a number sequence. Be warned though: spirolaterals can be very addictive! You can create your own spirolaterals by entering a number or text like your name. Or you can explore the gallery of 80 spirolaterals by tapping Surprise Me! Spirolaterals raise many interesting questions: Which ones repeat and why? What kinds of symmetry are present? What happens when you use a palindrome or when your numbers increase or decrease by the same amount? I have used Spirolaterals in my math classes for many years, and students always find them fascinating. They try their name or phone number. They try to create some particular pattern. This year some students spent hours trying to create a 4x4 grid! If you create an interesting spirolateral, email me and I may include it in the Surprise Me! gallery in a future version, with full credit to you!