Students were then challenged to invent a new machine to help decrease work using principals of one of the six simple machines.
(Students; were challenged; to invent a new machine to help decrease work; T:then) (Students; to invent; a new machine; to help decrease work) (a new machine; to help; decrease work using principals of one of the six simple machines)
Students Students a new machine
were challenged to invent to help
to invent a new machine to help decrease work T:then
a new machine to help decrease work
decrease work using principals of one of the six simple machines