Not exactly a time machine, but if you work with elementary students, this activity might be a useful combination of grammar and speaking practice. Short and concise, it will allow you to add an extra word on prepositions + religious festivals and as well as some longer stretches of time. Still, you will be able to finish your lesson on the dot of the hour :) 

prepositions-of-time-survey-conversation-topics-dialogs-grammar-drills-icebrea_131502.docx

Prepositions of time - survey

prepositions-of-time-survey

Let's do English ESL general grammar practice. Not exactly a time machine, but if you work with elementary students, this activity might be a useful combination…