Take a look inside a cell.  Click on an organelle to zoom in and explore the cell part.  You can select views of both plant and animal cells.

This interactive animation of the Molecular Biology of an HIV Infection gives students a visual understanding of HIV progression.  It starts with the encounter, particle engulfed, capsid dissolves, reverse transcription, genome insertion, expression, and destruction paths, including budding and syncitium formation.

From site:  In the Clay Cell activity, students build 3-d models of cells, organelle by organelle. Once the clay dries, the cells are sliced and the resulting cross-sections are examined.

From site:  BioEd Online Classroom Lessons are inquiry-based, field-tested, standards-aligned activities and supplemental materials that can be downloaded as PDF documents for use in your classroom. Materials are sorted by topic and grade level, making it easy locate lessons that are appropriate for your students.