Explaining to my grandchildren that the consecrated Eucharist is held in a ciborium and displayed in a monstrance is a foreign language.  

Yes, the priest consecrates the hosts to become the Eucharist but there are times when the Eucharist is needed outside of Mass.  People who are sick and can't come to Mass need the Eucharist too.  That's why some of the Eucharist is put in a ciborium and placed in the Tabernacle.

Also, the Eucharist is sometimes venerated in a monstrance.

Ciborium:  the vessel used to distribute the Eucharist

Monstrance: a decorated frame containing a Eucharistic Host

Consecrated Host: The Eucharist.