In my first lab notebook experience I had students in the middle school write up their own lab chart in their book (see first picture) . Students really struggled with drawing a chart (top of the page) to collect data over this multi-day experiment. The picture above was from the notebook of a good student but even she made it so small it was hard to read what data she collected day-to-day. I learned my lesson and from then on out provided lab sheets to glue into the book.
The bottom picture is of the same identical experiment a year later (we did it at the start of the fourth grade year) but because I had made up a lab sheet for the experiment it was much easier for students to record information and for me to read.