CK-12 Foundation
Ck 12: Positive and Negative Fraction and Decimal Comparison Grade 6
[Free Registration/Login may be required to access all resource tools.] Compare and order positive and negative fractions and decimals.
Khan Academy
Khan Academy: Absolute Value of Complex Numbers
Given a complex number in the form a+bi, find its absolute value. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints. HSN.CN.B.4