The following lesson is aligned to the NGSS standard:
MS-LS1-1: Conduct an investigation to provide evidence that living things are made of cells; either one cell or many different numbers and types of cells.
A lesson plan is in the last few pages of the document. I taught this lesson before teaching the students anything about cells or living organisms, and I was pleasantly surprised to hear many of the students describing characteristics of a cell when they looked at the slides of the living samples. One of my colleagues taught it after doing some readings and videos on cells, and it reinforced what he had taught.
My first year doing this lab I used microscopes and slides (what slides I used are in the teacher notes), but unfortunately our microscopes were not inn great shape so the second year I created some documents for the students to view in google classroom instead. They were disappointed that they wouldn't use microscopes but in the end they were able to identify common structures and patterns in living and nonliving samples.
I have included two word documents for the known and unknown samples, but I removed the images that we used. These images were copyrighted, but a quick google search can help you find similar images.
At the end of this unit students use the venn diagram from this lab to identify a sample as living or nonliving on their assessment.