Do we need to know this ? Education Community › Physical Sciences › Grade 9 Physical Sciences › Do we need to know this ? This topic contains 1 reply, has 2 voices, and was last updated by Robert Maguire 3 months, 1 week ago. Author Posts November 6, 2018 at 10:01 PM #628 Cameron RoacheParticipant Intermediate Colearner do we need to know all the elements in the periodic table November 10, 2018 at 11:35 PM #653 Robert MaguireParticipant Intermediate Colearner You definitely don’t need to know all off by heart, but be familiar with the table. Your teacher might require you to learn the first 20 for some tests that don’t have a data sheet. Author Posts You must be logged in to reply to this topic.