After reinforcing the idea of a what a function is, this video jumps into working through mathematical functions. There are many videos that do this, but this one does so in a very clear, complete manner. In this video, functions are superbly introduced from which it progresses into domains and ranges.
There are fun ways to teach and then there are the rest of the ways. If you can get the class actively involved, students will retain more of the information. This blog is a great resource if you are looking for activities to do inside the classroom. Many students find it hard to engage with math, but how many math teachers have students running around the classroom and signing songs.
An excellent starting point from the Khan Academy that, in addition to this video, also offers an entire series of videos and exercises to guide students through the mastery of linear functions. The video itself offers a fewer more complex functions as examples and as is the case with most videos from the Khan Academy, it is concise, informative, and can of course be paused and replayed repeatedly.
It can be hard to write an infinite number of solutions on a test page. That is a lot of paper. Luckily, math has some helpful tools like graphs on which infinite solutions can be illustrated. This is a great walk-through from Sal Khan on how to graph a function.
This blog is great and it's author understands the importance of an analogy. Functions are machines, factories, algorithms... whatever you want to call them. But calling them something of this sort is a very important first step for students. This math teacher's blog give you some season advice for a tough unit.
Context! Relevance! Analogies! The roots of the Khan Academy are in mathematics and this is one of its several superb videos regarding functions. This is a another contextual gem, mimicking how a mathematical function works just like a grain mill, only for numbers. Enough cannot be said for any math video that can relate math and the real-world via analogies. Math is common sense in a sometimes confusing language.
It took me 33 years to laugh during a mathematics lesson. This is the lesson. I needn't say more, but this short video lays the contextual and conceptual foundation for learning about mathematical functions. If you are like me, appalled by the food industry, you are in for an extra special treat.