How to pause, and restart (without resetting), a timer block - ev3
I don't think there is a shortcut.  The timer sensors record how much time has elapsed since they were reset.  The starting of the program gives you the first reset for free.  So the psuedocode ends up something like this.  The button touched vs released is a personal preference.  I think of the interval as starting when the button is released and extending until it is pressed.  


Set a variable "totalTime" to zero
Loop start
wait for button touched
Set a variable "intervalTime" = timer sensor value
Set "totalTime" = "intervalTime" + "totalTime"
Set intervalTime = 0
wait for button to be released
write to the LCD display "ready for next interval"
wait for button to be touched
wait for button to be released
reset the timer sensor
Loop end (forever)