This website resource is of excellent quality and would be a recommended resources for teaching explorations to Junior Certs.
First man to circumnavigate the world. Contains really accessible material for pupils to read.
Additionally contains an excellent map from the exploration period.
More often than not it is asked in Q4 People of history and can also be asked in the document or picture based questions as well as the short questions.
Pictures like these are imperative and should be used more often in the class as they are primary sources and gives them a fuller understanding of the period that they are studying.