Meiosis

Meiosis is an important process that occurs in sexually reproducing species. Its purpose is to create gametes, which are special cells contain only half of an individual’s DNA. In humans and many animals, meiosis creates gametes called sperm and egg. In plants, these gametes are called pollen and seed. Gametes eventually combine with another gamete from an individual of the opposite sex to form a zygote, or fertilized egg.

Meiosis vs. Mitosis

Meiosis and mitosis have many similarities. They both begin with interphase, in which the cell copies its DNA. They also both include the phases: prophase, metaphase, anaphase, telophase, and end with cytokinesis. Unlike mitosis, though, meiosis requires two divisions. The first division (called meiosis 1) does not reduce the chromosome number; the cell would still be considered diploid. After the second division (meiosis 2) the chromosome number is reduced by half and the cell is now haploid. Mitosis is a form of asexual reproduction, and is intended to maintain the number of chromosomes in a cell. Mitosis results in the formation of identical daughter cells. Meiosis, on the other hand, is a process that prepares for sexual reproduction. Meiosis seeks to increase genetic variety as much as possible which helps the species adapt to changing environments. Let’s look closer at two ways meiosis builds in genetic variation to the gametes it produces:

Crossing Over: During meiosis, a special process occurs in prophase I. Crossing over is a process in which homologous pairs of chromosomes exchange some of their DNA. This further increases the genetic variety present in the gametes produced.

Independent Assortment: In anaphase I, the homologous pairs are split apart. Which chromosome goes to which side is completely random, further increasing genetic variety.

Meiosis Stages

Prophase I: The nuclear membrane dissolves and chromosomes condense. Homologous pairs form tetrads and crossing over occurs.

Metaphase I: Homologous pairs line up at the cell’s equator.

Anaphase I: Spindle fibers pull each of the two homologous pairs to opposite ends of the cell. Unlike mitosis, sister chromatids are not split apart.

Telophase I: Chromosomes are now at opposite poles of the cell. Depending on the species, the nuclear membrane may reform and the chromosomes uncoil. In other species, these steps will not happen since the whole process is about to begin again. At the end of telophase I, the original cell splits into 2 new cells.

Prophase II: Cells begin their second round of meiosis without replicating their DNA. In prophase II, the nuclear membrane dissolves again and DNA condenses.

Metaphase II: Chromosomes align at the equator of the cell.

Anaphase II: Spindle fibers pull sister chromatids to opposite ends of the cell. The centromeres are finally broken.

Telophase II: Both cells divide, creating 4 haploid cells. Each cell has exactly one half of the original cell’s DNA, or one of each homologous pair.

Learn More About Meiosis

Guided Practice

A 6 page practice with in depth descriptions of the stages of meiosis, summarizing questions, and a graphing extension.

Get it here.

Webquest

A best selling 4 page webquest that allows students to dive deeper into the topic on their own.

“Excellent resource for initial investigation OR review!”

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Color by Number

Practice identifying similarities and differences using this fun worksheet!

Great way for my students to remember the differences between mitosis and meiosis. Plus, they love the coloring. Thank you for a great resource!

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Learn more about how I plan my unit on the cell cycle here.

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Evolution Unit – Teacher's Guide

Welcome! This post has been written with the intention of helping you plan an engaging and comprehensive Evolution unit for your middle school science class. If you’re arriving to this page from somewhere other than the Teachers Pay Teachers site, this is the product that this guide was written for. Here’s how I teach using these resources:

Note: Items are listed in the order in which they would be used. Lessons are not broken into specific “days” as many of us have vastly different timings per class period. 

  1. Natural Selection Presentation
    I’ve moved away form a lot of teacher focused instruction, but I can’t resist the urge to tell the story of Darwin’s journey on the HMS Beagle! I usually follow this lesson up with one of the several Youtube videos that cover this same journey.
  2. Evidence for Evolution Presentation
    This presentation covers the main evidences for evolution as described by the NGSS standards.
  3. Homologous, Analogous, and Vestigial Structures Practice
    Use these fun examples to examine the skeletal structures of several vertebrates. Are some ancient signs of evolution still present in their anatomy? It’s one of my best sellers!
  4. Punctuated Equilibrium Case Study
    Use this case study on tuskless elephants to discuss the possibility of rapid evolutionary change in a species. It’s happening in our world today as elephant populations become more and more tusk-free in the face of poaching pressure.
  5. Sub Plans: Darwin Awards
    A little morbid I must admit, but the kids love these hilarious Darwin awards. What’s the dumbest way to die?
  6. Darwin’s Theory Quiz
    A quick formative quiz to check for understanding.
  7. Inquiry Based Online Evolution Lab
    I absolutely love this lab. It covers fossil evidence of evolution and also vestigial structures. I’ve used it for several years to teach evolution in an inquiry based way, and also to reinforce the practices of scientists. Last year I even extended this portion of our unit and had the students write a formal lab report.

This product is designed to be affordable and useful to teachers in middle school science. Help me serve you and others through this bundle (or the creation of new resources) by leaving feedback. My work is meaningful when it takes some of the stress off of YOU.

Teaching is a weird job. I’d love to connect and discuss our successes and failures on my instagram (@laney.leee).  Please reach out and ask me anything.

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DNA Extraction Lab

I have to admit, even though I’ve been teaching science for 8 years, I was scared of the DNA Extraction Lab. I knew it was simple; I’ve done the process myself. Rather, I concerned about classroom management and where I’d find all the materials. I had nightmares the night before as I envisioned my classroom going crazy. All for nothing, it turns out. This lab is simple and easy to implement! I’ve prepared this step by step guide for you so that you can bring the joy of hands on science to your classroom too!

Lab Materials:

  • Strawberries/kiwi (at least 2 per group)
  • Zip lock bags (one per group)
  • 2 tbs dish washing liquid per group
  • 2 tbs salt per group
  • 1 coffee filter per group (or cheese cloth)
  • 1 clear plastic cup (or any other clear glass lab equipment) per group
  • ¼ cup cold rubbing alcohol per group
  • 1 coffee stirrer per group
  • A few extra plastic cups for passing out materials
DNA Extraction Lab Strawberry

Rubbing alcohol is a perfectly good substitute for ethanol – like you’d get in the pharmacy section of any grocery store.

DNA Extraction Lab Strawberry

Any salt and any dishwashing soap will do!

DNA Extraction Lab Classroom Setup

I split my students into groups of 3 and 4 for this lab. To keep everyone engaged, I make sure each student got their very own strawberry to smush. I give every student a copy of the DNA Extraction Lab Student Sheet also. Everyone is required to complete and submit the lab sheet upon completion of the lab.

If you’re using my lab sheet, I like to read the included page on the history of DNA and the reasons for each step of the extraction process. This is a great extension if you’ve taught Cells or the Cell Theory yet.

DNA Extraction Steps

  1. Give every student a strawberry, or at least 2 strawberries per group. Have the students remove the leaves of their berries.
DNA Extraction lab Strawberry

2. Pass out a zip lock bag to each group. Set a timer (I like 5 minutes for this step.) for the time each group will have to smush their strawberries. Emphasize that the bag should be passed to each group member and they will get their turn to smush the mixture. Remind the students that they want a very liquid consistency by the end.

While the students are busy smashing away, I like to prepare the mixture for the next step. I make a small cup with salt (a couple tablespoons), dish soap (a tablespoon or so), and maybe a third or fourth a cup of water for each group. Exact measurements are not a concern.

DNA Extraction Lab Strawberry

3. Pass out the cups filled with DNA Extraction Liquid. Have the students pour the whole cup full into their zip locks and then smash the mix up a little bit more.

As students do this, I pass out one clear cup to each group and a coffee filter.

DNA Extraction Lab Strawberry

4. Students will now strain their strawberry mix through a coffee filter (or cheese cloth) to remove the solid pieces. They’ll need to have one student hold the filter and cup while another student pours.

Students may want to really wring out the mix. That’s a great idea! Get as much liquid as you can from the strawberry mix!

While students complete this step (which tends to be a very messy and exciting one), prepare cups with a fourth or third cup of cold ethanol or rubbing alcohol.

DNA Extraction Lab Strawberry

5. Pass out the cups of rubbing alcohol and instruct students to carefully pour them into their clear cup of strawberry liquid. They should pour down the side of the cup not directly into the mix so that they do not damage the DNA.

6. At this time, students can throw away and clean everything except the clear cup of strawberry liquid. I like to nominate one student to wash all the ingredient cups so that they can be re-used.

It takes just a few minutes for the DNA to precipitate from the mix.

DNA Extraction Lab Strawberry
DNA Extraction Lab Strawberry

7. Using a coffee stirrer, allow students to remove the DNA from their cup to touch and examine!

DNA Extraction Lab Strawberry

To help you in the classroom, I’ve created a version of this process on Google Slides that you can display on the board as you go through the lab.

Click here to download the free step by step presentation.

Additionally, if you’re interested in my student lab sheet, it’s available for download here.

Finally, if you’d like to learn more about how I teach my DNA Unit, check out this blog post for a teacher’s guide!

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Cell Theory

Cell Theory Definition

The cell theory is a widely accepted and proven set of three ideas which describe life at a microscopic level. The three parts of the cell theory are:

  1. Cells are the most basic unit of life.
  2. All living things are made of cells.
  3. Cells only come from pre-existing cells.

Cell Theory Timeline

Beginning in 1665, Robert Hooke is credited with first using the name “cells” to describe the tiny rooms in the cork he was able to see using a microscope that he designed himself. Although he had no idea that he was witnessing the building blocks of all life, his discovery laid the foundations for modern microbiology.

Not long after that, Francisco Redi performed a famous meat experiment in 1668 that helped to disprove the concept of spontaneous generation which was widely accepted at that time. Spontaneous generation is the idea that living things can pop into existence out of non-living things. For example, at the time, people thought that maggots (fly larvae) “spontaneously generated” or arise from old meat rather than being born of parent flies. Redi disproved this idea with an experiment in which he covered a piece of rotting meat with a cloth that blocked flies from reaching it. No maggots developed from the meat.

Later, Anton Van Leeuwenhoek developed his own microscope using a technique that required grinding glass lenses. As a matter of fact, he was so successful in his craft, that there was no further progress in the development of the theory for over 100 years! Leeuwenhoek was a curious man and looked at a lot of different samples with his lenses. He observed everything from pond scum to teeth scrapings. He saw the first living cells (bacteria) in 1674, and called them “animalcules,” thinking they looked like tiny animals.

(Note the large gap in time since anything was done to develop the theory.)

Finally, in 1827, Robert Brown first described the nucleus of a cell.

In 1839, Matthias Schwann studied animals and determined that they were all made of cells while Jakob Schleiden did the same with plants. Together, they developed the second tenet of the cell theory.

In 1855, Louis Pasteur further settled the matter of spontaneous generation with an experiment using meat broth. Through his work, he was able to prove that even microscopic life can only come from other life. This discovery led to the process of pasteurization (named after him) which involves boiling liquids, such as milk, for sanitation reasons.

In 1855, Rudolf Virchow finally settled the matter of cell reproduction after watching cells divide. He famously wrote Omnis cellula e cellula which means that cells only come from cells. This idea went on to become the third tenet of the cell theory.

Learn more about the cell theory:

Cell Theory

Guided Reading

Use this comprehensive reading with questions as an introductory activity or for reteaching. Great as a review before a test or as homework!
Get it here.

Cell Theory

Practice Worksheet

Use this best selling review. Students use answers to fill in a riddle that makes this worksheet self checking!
Get it here.

“Students really enjoyed doing this activity.”

Cell Theory

Quiz

A quick an easy quiz to review the scientists who made contributions to the Cell Theory.
Get it here.

“Perfect activity to use for review, homework, or a quiz. Simple and effective! Thank you.”

Learn more about how I plan and teach my cells unit here.

My teaching resources have already benefitted the learning of over half a million students. Please pin the image below to help me expand my reach.

Cell Theory

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Why I Incorporate Coloring Time in my Middle School Classroom

One of my favorite classroom management strategies is mandatory coloring time. I use this activity once per unit. Everyone gets a different word wall word (purchased through TPT) and I also supply the coloring supplies. Then I set a timer. 30 minutes. You can finish late but you cannot finish early. (This is to stop those kids that zoom through everything.)

During mandatory coloring time you’re allowed to listen to music or sit however you like. Most kids choose to just chat though, with me and with each other. We use this time as a brain break. A chance to relax and enjoy one another.

Although this coloring time may not be considered “bell to bell” instruction by strict administrators, I believe it’s one of the most important things I do for classroom management. It’s my chance to step out of the role of “The All Knowing Answer Giver” and simply spend time relating to the kids. I chat with them and find out what their interests are or what they’re currently watching on Youtube.

You’ve probably heard before that the most important part of classroom management is relationships, so why not take time to build them?

A Charge for Veteran Teachers

In our school this year we have exactly one first year teacher. ONE. That means we have lots and lots of veteran teachers. The new teacher just so happens to be my friend, and she often expresses to me a feeling of being judged or looked down on. My question is this: where does this attitude stem from? Why are we, as teachers with more experience, not rallying around the newbie in our school to support her?

I’m going to tell two stories, one from her perspective and one from my own. My first year teacher friend is (no surprise) having some issues with classroom management. How difficult it is to learn how to manage 5,000 different decisions a day overlapping with 30 children’s unique personalities. Making the right choice all the time is impossible for all of us, especially for someone with less experience.

Recently, my friend told me a story of how another teacher invited herself into my friend’s classroom while she was teaching. From there, she proceeded to dominate the situation. She completely took over classroom management, demanding everyone get back on task. At one point, she leans over to my friend and reassures her. “I’m here to help and support you.” When my friend told me the story, it was obvious that the situation made her feel small. Since when was undermining another teacher or commanding their classroom a form of support? In this day and age of informed consent, would it have not been better to whisper a question first? Something along the lines of “Do you mind if I correct some children?” or even “How would you like me to support you?”

The second story I witnessed for myself. My friend bravely called a meeting of all the teachers who have a certain group of kids. The hope was that management strategies could be shared for everyone’s benefit. The meeting was to begin right after school finished. The first to arrive was a seasoned veteran teacher, exactly 45 seconds after the bell. As I happened to be the only other person standing by and no one had shown up yet she directed her question to me.

“Is this the room we’re going to be meeting in?”

“Probably?” I responded.

“Oh. I guess I’m the first one here then,” and then she leaned in and whispered to me, “I guess it’s because my class actually had their act together to be able to leave on time.”

Now, maybe I’m reading too much into things, but that comment sounded extremely judgey to me. I could be wrong, but I’m going to continue this blog post as if she meant what I think she meant. I think she was taking a stance of superiority in the fact that her classroom is more well run than someone’s who has been teaching for approximately 1.5 months. You don’t say?

As experienced teachers, I’m sorry but we’re going to have to do better. We’re going to have to stop using the failures of new teachers to build up our own egos. We’re going to have to remember what it felt like to be new and terrified. We’re going to have to create an atmosphere where vulnerability is SAFE and not rewarded with judgement. We’re going to have to look more critically at ourselves and stop assuming that just because our room is silent that we’ve got it all figured out. We’re going to have to be critical of ourselves too. We haven’t arrived. We’re still learning too.

I can’t believe that in a building full of experience, our only new teacher is afraid to speak up about her struggles. I am shocked that the “support” she does get feels more like a form of bulldozing or “watch what I can do.” I find it even more ironic that we are TEACHERS. Read that again. TEACHERS. Isn’t our passion supposed to be helping people improve? Are our egos so fragile that we genuinely think this is a zero sum game? If someone else succeeds then I must be failing? It’s time to drop the competitive mindset and build each other up.

My TPT Journey: The RAW Data

I see so many people who are just dying to know how long it takes to make decent money on teachers pay teachers, so I wanted to take this chance to just lay it all out. My journey has been an extremely long one. I didn’t get serious about what I was doing for about 3 years, and then again after I started making over $500 a month I took another step up in terms of my intensity. Now that I’ve had my first $1000 month, I’m changing my perspective once again.

Here’s how it went for me.

Total Number of Products in my Store

  • 2013: 38
  • 2014: 39
  • 2015: 56
  • 2016: 117
  • 2017: 168
  • 2018: 217
  • 2019: 260 (as of writing this on Oct 25)

That means I created 38 products my first year in 2013, 1 in 2014 (what happened, Laney?), 17 in 2015, 61 in 2016, 51 in 2017, 49 in 2018, and 43 so far in 2019. Working full time as a teacher and creating products isn’t easy. It’s very difficult to create more than one per week, when things are going well and you feel inspired.

I wouldn’t neglect to factor in the fact that there have been extensive times where I didn’t care about Teachers Pay Teachers at all and I’ve done virtually nothing for my store. In fact, it appears that all of 2014 was that way for me. Prior to maybe 2015, though, I had no covers in my store and just posted things I was using in my own classroom because I figured, why not?

My Earnings

Ah yessss. The good stuff. As you can see, my store didn’t turn into anything that anyone would shake a stick at until 2017. I finally started to advertise and create previews. More importantly, I started to get the idea that this website could one day really pay bills.

As you can see, I’m impatiently waiting for my first milestone ($20,000 in total earnings).

Page Views

Because I spend so much time (and money) on advertising these days, I’ve begun to take my page views more seriously. I need to know that I’m really driving traffic to my store.

Units Sold

This last one may be the one that means the most to me. Units sold tells me how many teachers have trusted me enough to give me some of their hard earned money. It’s how many classrooms my work is in and how many people’s day I’ve made a little easier. It’s the real reason I stay at this little side gig.

I am so grateful to my customers, and I want to honor them with my hard work and product creation.

Check out my store and tell me what you think!

How to Print as a Booklet

Immediately after I learned how to print as a booklet I got hooked! I love saving paper and plus these mini books are also just so cute! In my old school the copier could do it , but now I have to print my booklets in a different way. This method works for anyone who has a printer!

Here’s how to print a booklet from any PDF:

To start, you’ll need Adobe Reader. Don’t worry, it’s free!

Once you have that installed, open your PDF in the Adobe Reader.

Example of how your PDF should look once you’ve opened it in Adobe.

After that, click print and select the booklet option here:

Click the “Booklet” option.

Now your PDF will print and easily fold in half to make a great booklet!

How I’m Teaching Cells and Photosynthesis this Year

First off, let me be honest. I hate this unit. I find the cells unit to be a mile wide and an inch deep.

The only thing I hate more than cell organelles is photosynthesis and respiration. At my school we teach a discipline of science per year. It’s Earth & Space Science in grade 6, Life Science grade 7, and then finally Chemistry and Physics in grade 8.

What that means for me is that I’m attempting to teach the important chemical reactions of life, photosynthesis and respiration, while my students have absolutely no idea what a chemical reaction even is.

Later, I teach DNA and proteins, but my students only vaguely know what a molecule is! Much less how or why they form!

I’m sure you can sense my frustration.

In some past years, I’ve taught a short chemistry crash course in an attempt to give my students the prerequisite knowledge they really need. Ex-students have told me that it helped them when they took actual chemistry, so I decided to do that again this year.

Here’s how I did it

I started the second day of school with the characteristics of living things. We made posters and hung them up so that I can refer to them throughout the year.

Then, I went directly into my chemistry crash course. I taught atoms, elements and the periodic table first. From there, we went briefly into valence electrons to explain what a molecule is. Yes, I know that’s quite a lot for a week, but it’s not actually my content!

I think I had an ah-ha moment from most of my students when they saw why water forms. I expanded from there by showing them other important molecules we’d be studying throughout the year: glucose and a protein.

I really hoped through this that my students will see why the atoms in molecules are so strongly connected. These materials don’t just come apart like a mixture would.

Then we studied chemical reactions. I taught a lesson on the Law of Conservation of Mass and how atoms are rearranged in a reaction. I let them play around with the balancing equations PhET Sim. Some of them really took to it and away they went! Regardless, that’s not my standard so even the students who stayed on level 1 still got a lot more than what my past students would have known.

Then, I jumped right into photosynthesis and respiration. I explained that these are crucial chemical reactions to life and we looked at how the atoms are rearranged.

Next, I’m taking that that into organelles, beginning with the knowledge that chloroplasts and mitochondria are where these processes occur.

After that, it’ll be prokaryotes vs. eukaryotes. I’ll explain that the organelles we studied were eukaryotic and that prokaryotes are bacteria.

Once we know what bacteria is I plan on doing a case study on the human microbiome. And every year I also like to teach a day on antibiotic resistance.

I think I may actually skip the cell theory completely this year, as it’s not even in the NGSS standards. I also recently received a bad rating on my TPT store because a resource I created on famous scientists wasn’t inclusive enough. So considering the amount of old, white men involved in the cell theory perhaps I’ll just forget it this year! Ha!

So.. yeah! I think I’m going to basically be teaching this unit in reverse as compared to how I usually would have! I’m hoping some other middle school teachers will read this and let me know their thoughts!

After this, we’ll take a test and move directly into mitosis/meiosis. Then DNA. Then inheritance. Then evolution. Then ecology. And that’ll be a wrap!

My 2 New Product Lines!

I thought about it, and I think I mainly turn to Teachers Pay Teachers on days when I just can’t. I know I’m not the only one either because my webquests sell like hotcakes! Sometimes the lesson just isn’t going to fill period and we need some (meaninful) fluff. Other times we might need an idea to get us started for an entire lesson.

With that thought in mind I’ve decided to launch two new product lines based on the success of similar products in the past.

1. Guided Readings

First will be my guided readings. I’m really excited about these because this category already contains several of my best selling resources. I genuinely believe that reading is crucial in the science classroom for language acquisition as well as teaching our students to turn a critical eye on the sources they encounter. For these reasons, I’ve been incorporating more and more reading into my own classroom this year.

If you’re interested in incorporating a little bit more old fashioned reading into your middle or high school class, start with my freebie on Atoms & Elements to see if my style is the right fit for you. As I continue to expand the product line, I’d love to hear your suggestions on what topics you’d like to see covered.

2. Vocabulary Crosswords

Academic vocabulary is difficult for all learners! I work with primarily bilingual students, but I used to have this same problem in the US as well. Students absolutely must practice with the words they’re going to encounter on quizzes and tests. I’ve designed this new product line to help you with early finishers and differentiation.

A quick crossword is a great way to fill in 15-30 minutes on the fly, and it requires nearly no help from you and best of all: no prep. Kids can do these on their own. I’ve included with each new resource 2 versions: one with a word bank and one without. If you need an extra assignment or two to throw into your emergency sub folder, check out my freebie on Organelles to get an idea of my vision.

The rest of my vocab crosswords are available here. And just like the guided readings, I’m happy to take suggestions for future products.

As always, don’t forget that leaving feedback can earn you credit towards future TPT purchases. I’m always happy to hear what you think!