I always start readers with a warm up exercise that's below their instructional reading level. Experts say children should read words in phrases rather than in isolation. Reading these phrases for a few minutes will have the children warmed up and ready for more instruction. The phrases can be read from copied sheets, or can be cut out and read as individual phrases for shuffling.
These phrases also work well for instructional work at the child's instructional level.
Experts recomment reading words in phrases to build fluency. These phrases support this Common Core ELA standard: RFS.4 Read with sufficient accuracy and fluency to support comprehension.(This standard is pretty much the same for all grade levels!)