My definition: An equation is a math sentence used to solve a problem.
3 + x = 10
V = ∏ r²h
My definition of a function: Input a number, the number goes through a math process and produces an outcome.
f(x) = 3x² + 5 (Read by saying f of x equals 3 times x squared plus 5.)
Supplementary resources that reinforce equations and functions:
Kid friendly definitions:
Students are given simple word problem and they practice writing the equation.
This link has another version of the function machine. Students put in an input of their choosing and the machine spits out the output. Students then come up with the rule.
This site has a simple game to play with the function machine.
Journal entries: To determine background knowledge I would have students record their definitions of equations and functions before the lesson. Following the lesson they would go back and revise their definitions and provide examples.
Reference: Pizza image came from http://mathspig.wordpress.com/category/lists/10-best-maths-funnies-of-2010/