Original sentence: The mixer truck spins its drum to make strong concrete for building.
Better sentence: The mixer truck spins its drum to mix strong concrete for buildings.
Why this is better (easy steps):
- The truck is the subject and spins is the correct verb — that part was fine.
- Use the word mix because the drum mixes the ingredients together, so the concrete stays the same and does not harden inside the truck.
- Say buildings (or "for building things") to show the concrete is used to make places like houses or schools.
One more simple option: The mixer truck turns its drum to keep the concrete mixed.
Short explanation: The drum turns so the concrete stays wet and ready to use when builders need it.