This is the 12946th most frequent Russian word.
линейке
The Russian word "линейке" is the dative or prepositional case of "линейка," meaning "ruler" (for measuring) or "lineup" (e.g., assembly).
In this sentence, 'линейке' is used to mean assembly, which is a gathering of students at school.
На школьной линейке выступают учащиеся.
Students are performing at the school assembly.
Here, 'линейке' once again refers to the tool known as a ruler used for measurement.
Длина нарисованных линий измерена с помощью линейки.
The lengths of the drawn lines were measured using a ruler.
Here, 'линейке' refers to a physical ruler used for drawing lines.