Plant vs. Animal Cells
Lesson 2 of 6
Objective: Students will be able to differentiate between plant and animal cells, and identify the three principles of cell theory.
To begin this lesson, I return the atoms and cells probe from the day before, and ask the students to provide answers to the following questions:
Who has cells?
Where do cells come from?
How do cells produce other cells?
Are cells alive? – What functions do they perform that non-living things do not? (Does a cell eat, breathe?, pee?)
I then tell them that the answers to these questions sparked controversies since, as always, scientists could not really agree on the answers, and present Lauren Royal Wood's Wacky History of Cell Theory.
I tell the students that we will hear a song Mr Tamez's Cell Theory song, and their job is to write down the three ideas in Cell Theory. I like playing this catchy song, and most often I have students dancing to Cell Theory. What often amazes me is that by the end of the song, the students sing along, and even months later, all it takes is the beat for the students to remember cell theory.
As we continue, I bring out a previously prepared cell sort in neat piles (when you make the cards, make sure you cut out the names of the organisms) and make a big production of tripping and making the card sort fall all over the floor. I tell the students that I need their help to re-sort the piles into plants and animals, so that we can proceed. I tell them that while they are sorting, they must create at least two "rules" - this means that all the cards they put in a particular pile must follow those two rules (NGSS Practice 2: Constructing mental and conceptual models to represent and understand phenomena).
I intentionally have plants that are not green, as well as animal cells obtained using FEM, so that color is not the rule.
As the students are working, I circulate the room, offering names of visible organelles, as well as challenging the rules they are creating, as appropriate. Some of the cards are rather tricky (for example smiley grass cross section), but what I am looking for is a basic "plants have cell walls (and often chloroplasts) which make cells look boxy, while animal cells are more irregular". Can you find this group's definition of "irregular shape" in the video?
As students begin to complete the task, I have them visit other sorts, and discuss their "rules" with each other. This develops a sense of commonality as the students realize that they came to similar conclusions even if they did so through different pathways. If groups differ on their ideas for placement of a card, I intervene facilitating the discussion that validates the rules both teams created.
I thank the students for being so incredibly helpful after my clumsiness, and tell them that since we are running out of time, we are going to watch a brief segment of a Bill Nye video on cells. They are responsible to write down three things they find interesting from the video in their notebooks.
Finally, a couple of minutes before the bell, I ask the students to use a post it to tell me one thing they did not know about cells, that they learned today AND that they have documented in their notes. Within this deliverable, I also ask that they inform me of anything they are unclear about, "so I can plan our next steps".
Teacher's note: This is not a graded deliverable, just a quick check for understanding of the lesson. But don't skip it - it holds students accountable to THINK! It also let's you see what they would like more information on.