In your studies of the periodic table you would have learned about the periodic manner in which physical and chemical properties of elements in the periodic table change.
Popular television programs sometimes fudge science for the sake of entertainment. The second video is a clip from one such program. It deals with the pattern in chemical reactivity of group 1 (alkali) metals.
In addition to being about patterns in reactivity, this is an exercise in making observations and drawing conclusions from them. You must pay close attention to what is shown as well as said in order to succeed in this task.
The resources listed below (all PowerPoint Slides) are all to be found on IGCSE Chemistry Periodic Table page.
The Discrepant Event
The following video shows the reactions of lithium, sodium, potassium, rubidium and caesium with water.
The following video is a clip from one of the experiments Brainiac Scientists perform in one of their programs. In this particular one, they purport to demonstrate the reactions of rubidium and caesium with water in addition to the other alkali metals.
And the questions is: Did the Brainiac Scientists actually use rubidium and caesium?
(Your answer cannot be just a yes or a no, obviously. You MUST provide at least a few evidences from the video to support your answer. The evidences can be not just visual, what you see, but also what you hear and what they say.)