Houghton Mifflin Harcourt
Holt, Rinehart and Winston: Homework Help Independent Practice: Arithmetic Sequences
Get independent practice working with arithmetic sequences. Each incorrect response gets a text box explanation and another try. Correct responses are confirmed.
National Council of Teachers of Mathematics
The Math Forum: Finding a Term of an Arithmetic Series
This site from the Math Forum contains a common question asked by students learning about arithmetic series which is answered by Dr. Math in a format that is understandable for all ages.