Curated OER
Arithmetic Patterns
Introduce your young math scholars to functions. Because the answer is explained at the bottom of the page, consider projecting this and covering it up until you hear the class responses. They observe a rule (in this case to add 15) and...
Shodor Education Foundation
Shodor Interactivate: Whole Number Cruncher
Put a number, the input, in the Whole Number Cruncher. See if you can discover the rule that gives you the result, the output. Directions are just a click away.