Final answer:
Jack is determining his reading speed by calculating his lines per minute (lpm). To do this, he divides the total number of lines read by the minutes spent reading.
Step-by-step explanation:
When Jack is counting the number of lines per minute (lpm) read, he is determining his reading speed. This activity may be part of a process to improve fluency or to gauge his reading level for classroom activities.
Reading speed is calculated by counting how many lines of text are read within a certain time frame, usually one minute. To calculate his lpm, Jack would take the total number of lines he has read and divide it by the number of minutes spent reading. For example, if Jack read 120 lines in 2 minutes, his reading speed would be 60 lpm.