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Math2
Math2.org: Series Convergence Tests
This is an excellent resource! It states all of the most common tests for series convergence. Examples are not included.
Khan Academy
Khan Academy: Converging and Diverging Lenses in a Lab
This passage will test your knowledge on lenses.
FNO Press
From Now On: Filling the Tool Box
Dr. Jamie McKenzie offers this comprehensive look at how to help students develop questioning skills. Practical suggestions for how to implement the ideas are also included.
BBC
Bbc: Gcse Bitesize: Lenses
Lenses are precisely shaped pieces of glass that have been developed and used in corrective glasses, telescopes, microscopes, binoculars, and magnifying glasses. They can be convex or concave. Links are provided to a video an a test.