PBS
Pbs Teachers: Is Love in Our Dna?
Participate in an online poll to discover what features instinctively guide people when choosing a mate. Consider which traits, both physical and social, are "universally" considered attractive to potential mates, and why.
US National Library of Medicine
Medline Plus: Blood Transfusion
This site explains situations which call for blood transfusions and describes possible safety risks of this procedure. It describes how this procedure occurs and provides a discussion of possible blood substitutes.
ClassFlow
Class Flow: Estimation
[Free Registration/Login Required] After this lesson, students will be able to solve problems using a variety of mental math strategies.