In this animated object, students observe how ATP energy is used to move substances across the cell membrane from an area of lower concentration to an area of higher concentration and when something too large needs to get in or out of a cell.
In this animated and interactive object, learners examine the definitions and formulas for radius, diameter, circumference, and area. Students also solve practice problems involving the circumference and area of a circle.
This learning object shows how blood droplets are held together by a strong cohesive molecular force that produces surface tension in each drop and on the external force. Surface tension pulls the surface molecules of a liquid toward its interior, decreasing the surface area and causing the liquid to resist penetration.