This is the 1091st most frequent Russian word.
ракетами
"Raketami" means "rockets" (instrumental plural form) in English.
The word "ракетами" is instrumental plural, indicating the tools or objects being used—rockets were the subjects of study and operation in this sentence.
Они учились управлять ракетами.
They learned how to operate rockets.
Here, "ракетами" also appears in the instrumental plural, describing the toys being used during an activity—playing.
Играть с ракетами на площадке было небезопасно.
Playing with rockets on the playground was unsafe.
The form "ракетами" is utilized to indicate the instruments utilized during these specific tests—rockets.