Shadows Science Lab: You can use this as a sample lab to show your students how labs are written. I uploaded it in Word format so that you can edit it as you please.
To make it easier for your students you can keep the title, aim, materials, hypothesis and method as they are with all of the information already filled out for them and only ask them to fill in the part which asks about the variables and the results. For younger children, you can leave out the conclusion, discussion, and processes