Instrument / Mediator
With what or through what does it happen?
Meaning
The tool, medium, body part, system, channel, or mediator used to perform or transmit the action.
How to spot it
Ask what tool or channel makes the action possible.
Examples
knife|phone|car|email|hand
with a knife|by email|through the app
He cut the bread with a knife.
Visual guide
Actor │ uses ▼ Instrument / mediator │ makes possible ▼ Action He cut bread with a knife.
Same role, different shapes: with a knife (preposition) knife-CASE (case ending) by email (medium) through the app (channel) hand + cut (bare/compound) Ask: with/through what?
Language View
In your native language
English usually expresses instruments with prepositions, especially with.
She cut the bread with a knife.
with a knife = instrument
In your learning language
Instruments are usually expressed with 'con' or another prepositional phrase.
Cortó el pan con un cuchillo.
He/she cut the bread with a knife.
Learners may overgeneralize 'con' where Spanish prefers another preposition or construction.
Same block, different coding
Both languages use this block strongly, but they signal it differently. Focus on form changes, not only meaning.