Why Do Leaves Change Color in the Fall?

 

Why do leaves change color in the fall? This is the question I posed to my ten-year-old daughter when we took a short trip to Maine this month. I gave her the assignment of doing some research on the topic and writing a response. When I read what she had written, I thought that she had done very well with her explanation. I told her that we should share it with others, who might enjoy learning from what she had written. She suggested I post it on my blog, so here it is! The following piece and the photo of foliage above were done by her.

The leaves change color in the fall because the leaves start producing less chlorophyll. If you are wondering, chlorophyll is a chemical that makes leaves green. Chlorophyll is responsible for photosynthesis, when plants take in water and carbon dioxide and use sunlight to make sugar to feed themselves. In the fall, there is less sunlight, which means less photosynthesis for the plants and less need for chlorophyll. When this happens, the trees prepare to go dormant in the winter. Without chlorophyll, the green leaves start turning into red, orange, yellow, and brown leaves. As the chlorophyll breaks down, the carotenoids, orange-yellow and brown pigments, and anthocyanin, red and purple pigments, are revealed and/or created. (Most anthocyanin is created in the fall.) That is why sometimes the leaves are not solid colors, but a mix of colors because the carotenoids and the anthocyanin are slowly being revealed and/or created while the chlorophyll breaks down.

I hope that you enjoyed reading my daughter's work and perhaps learned something, too!

If you are interested in other blogposts related to science topics we explored while on vacation, here are a couple of links:

Snow Science: Freezing and Melting Points the Same?!

Slime: Vacation Fun with Polymers!

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Personality Quiz with Plant Cell Parts

                                                                                                                            Updated March 5, 2024

You can use a fun personality quiz to get your students better acquainted with the parts of a plant cell. What plant cell part best matches each of their personalities? Do your students like finding out information and passing it on like mRNA does? Maybe they are full of energy, like the mitochondria, or leaders, like the cell nucleus. When I created this activity for my sixth- and seventh-graders last year, I was pleasantly surprised by how much they enjoyed it!

As I was preparing my lessons for a return to school after a long Spring Break, I wanted to come up with an activity that would ease students back into their studies and provide a review of cell parts. We had already completed the Cell City project on animal cells, and I wanted to reinforce what they had learned about plant cells. A friend shared with me the idea of relating cell parts to different types of people. My daughter had been taking various personality quizzes and suggested I create one for my students related to cell organelles. This turned out to be a great idea!

The plant cell personality quiz I created has a very simple format: a Google slideshow with personality types on each slide, all referring to the last slide, which reveals which plant cell part the student would be. The last slide also includes a description of what the cell part does. Here is an example of one of the personality type slides:

After discovering which cell parts they would be, students report their results on a Google Form. They explain why their personality matches the cell part. Students also need to report the result of one peer and give their opinion of whether the cell part is a good match for their peer’s personality. Grading this assignment was fairly easy because in Google Forms, you can view the quiz results in a spreadsheet, allowing you to view all the students' results at the same time.

Before giving students the personality quiz, I told them that I had some guesses about what their personality quiz results would turn out to be. As they completed the quiz and I asked them about their results, I found that I had guessed correctly on many though some were a surprise! As students shared their results with me and one another, this activity turned out to be a way to not only review plant cell organelles but also to connect with one another.

I have posted this Plant Cell Personality Quiz for free on TPT. Here's the link:

Plant Cell Personality Quiz on TPT

If you are interested in a project related to cell parts, follow this link:

Cell City: Cell Organelles Project

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FIRST LEGO League Robotics

Our FIRST LEGO League team members were so excited when they qualified for the tournament at Legoland! Servo Squad, the Museum School's robotics team, had spent more than a month preparing for the qualifying tournament. They built and programed their robot, created a project to present, and strived to work together as a cohesive team, following the FIRST Core Values. 

The FIRST LEGO League Challenge is for children aged nine to sixteen (there are additional programs for various ages). Students use creative problem solving as they design and build LEGO robots and program them to complete challenges that consist of manipulating objects made of LEGOs placed on a table covered with the Field Mat.

The theme and challenges teams complete change each year. Registered teams receive LEGO pieces for building objects needed for the challenges along with the Field Mat, which fits onto a table supplied by the team. (Our table was built by a team member's parent to meet the specifications.) Once set up, students have a near duplicate of the "playing field" they will use at an event.

At an FLL event, teams receive points for the challenges their robot completes. They are also judged on their robot design. Servo Squad was proud to take home a second-place trophy for robot design at a qualifier, and the points they gained in this area helped them move on to the next level of competition.

A third piece of the FIRST  LEGO League Challenge is the project. Students design a solution to a given problem that is centered around that year's theme. They must build or draw a prototype of their solution, and present it to judges at the tournament.

The fourth component of the competition is my personal favorite: following the FIRST  Core Values. Teams actually receive points for their conduct, and we found that this can truly be a game changer! I am proud to share that Servo Squad performed exceptionally well in the area of Core Values, winning a first-place trophy one year.  

The students' ability to follow the Core Values is tested while preparing for and taking part in FLL events, which can put teams under pressure. At the events, students must stay positive and keep their cool while presenting their robot and their project in front of judges. The most pressure seems to be on the robot operators, who launch their robots onto the playing field with music blaring, cameras on their robots, and announcers describing every outcome. 

Through all of this, the FIRST  Core Values encourage students to exhibit "Gracious Professionalism"  and "Coopertition", and to remember to have fun! 

After getting through some challenges related to team cohesion, Servo Squad learned the importance of teamwork and staying positive. When they got to the Legoland tournament, their robots did not perform as well as they had hoped. Despite this, they kept smiles on their faces and supported one another in enjoying themselves. The judges were so impressed with their upbeat attitude that the team walked away with the Judges' Award at the end of the tournament!

Focusing on the FIRST  Core Values is a key part of the learning experience as teams prepare for and participate in an FLL event.

One of the barriers to taking part in the FIRST  LEGO League Challenge can be the high cost of the robot and registration. Teams often fund raise to help with these costs. Our team decided to offer reasonably-priced after-school robotics classes to students in younger grades. This helped a bit with the cost and gave team members the experience of teaching and mentoring potential future members of the robotics team.

When students participate in the FIRST  LEGO League Challenge, they gain skills in programming, creative problem solving, and working on a team, all the while focusing on positive values that will serve them lifelong.

If you are interested in learning more about FIRST  LEGO League, you can follow this link:

https://www.firstinspires.org/robotics/fll

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Drooling Pumpkin Chemistry Lab for Halloween

 

In this Halloween chemistry lab, students create a jack-o-lantern that foams at the mouth! You can use the lab to address NGSS standard MS-PS1-2 as students observe properties of the reactant (hydrogen peroxide) and the bubbly products of the reaction.

I have used the "drooling pumpkin lab" with students in seventh and eighth grade. The class size has usually been about twenty-five students, and there has always been another adult in the room with me. This is helpful for managing materials and spills and to keep an eye on safety because sharp tools are required to carve the pumpkins. Students usually keep their behavior in check because they are excited to do the lab and know that safe behavior is a requirement for participation.

Students work at tables in pairs or small groups. They start by carving their pumpkin into a jack-o-lantern.

Before carving the pumpkins, be sure to put them onto a tray or paper to protect the tables because it gets messy! Suggest to students that positioning the jack-o-lantern's grin lower on the pumpkin will help the reactants flow out of its mouth. (After carving the pumpkins, you will have lots of seeds, so you could ask parents ahead of time if they would like to take some home to roast in the oven.) Depending on how much time you have with students, carving the pumpkins alone can take a full class period.

The reaction used to create the foam that oozes out of the jack-o-lantern's mouth is the decomposition of hydrogen peroxide, a liquid easily found in solution at pharmacies. Yeast is used as a catalyst in the reaction, so this is a good opportunity to teach students how a catalyst does not take part in the reaction but merely helps it happen. (I found a one-pound bag of yeast online and stored it in the freezer for many years.)

To activate the yeast, student groups mix a few tablespoons of yeast with a few tablespoons of lukewarm water in a small container and let it sit for about 5 minutes, forming a paste. Meanwhile, students pour about 1 cup of hydrogen peroxide solution into another small container and mix in a few drops of dish detergent. (I recommend using an unscented soap for students sensitive to smells.) The dish detergent will capture the bubbles produced by the decomposition of hydrogen peroxide, creating a foam.

Students lower the container of hydrogen peroxide solution with dish detergent into the jack-o-lantern, add the yeast paste, and stir. Soon, the reactants flow out of the pumpkin's mouth, causing it to drool! In some cases, positioning the container of hydrogen peroxide close to the jack-o-lantern's mouth can help students get this effect.

So, where did the bubbles come from? Yeast speeds up the decomposition of hydrogen peroxide into hydrogen and oxygen, and these gases are captured by the soap, creating the foam. Students can easily see that a chemical reaction has occurred!

If you are interested in other fun chemistry labs, you might like this blogpost on making "gel worms":

https://www.scientificcreative.com/2022/05/polymer-lab-gel-worms.html

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Classroom Icebreaker / Getting to Know You Activity: Venn Diagrams

Venn diagrams can be used as an icebreaker to help students get acquainted at the beginning of the school year. I have also used Venn diagrams as a team-building activity when beginning a group project. Venn diagrams are a simple, low-prep yet effective way to help your students get to know one another.

The format is very simple. You can use a two-circle Venn diagram for pairs or a three-circle Venn diagram for groups of three. When beginning a group project with teams larger than three students, you can break students into smaller groups and pairs. Whether I plan to have students work with a partner or in a small group, I always prepare a few copies of the alternative form of the Venn diagram in case the number of students present that day is not divisible by two/three.

After I tried having students draw the Venn diagrams themselves, I found that giving them copies of pre-made Venn diagrams works best because it is tricky to draw intersecting circles with spaces large enough to write. I have either drawn the circles myself to photocopy or found Venn diagrams online.

To begin the activity, ask each student to write his/her/their name just outside of one of the circles. Partners and groups of three talk about themselves- their interests, families, backgrounds, likes, and dislikes. In the space where the circles intersect, they write the things they have in common. Students note ways in which they are unique in the area where the circles don’t intersect.

Keep in mind that some students will begin conversing without much prompting, while others will need a little support. It can help to write suggested topics (favorite foods, hobbies, talents, number of siblings, pets, etc.) on the board and circle around to prompt students as they work.

When students finish, you may want to have them share with the class what they have learned about one another. I often ask pairs and groups to share one way in which they are alike, and one thing that made each student unique.

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Beginning of the School Year Activity: Decorate Room with Student Collages

At the beginning of the school year, two common priorities for teachers are classroom decor and getting to know their students. One beginning of the school year activity I have used does both of these things. 

The simple activity of having students make collages that express their personalities was shared with me by Ann Davis, who at the time was a parent of one of my students and working towards a Masters in Expressive Arts Therapy. My students and I were fortunate to benefit from her enriching activities, which helped students reflect, build self-esteem, and connect with one another. The collage activity she taught me is one I started using at the beginning of the school year. It invites students to express their individuality, and in doing so, provides an opportunity for members of the classroom community get to know one another better. 

To prepare for making collages, I begin collecting magazines and other paper media with a variety of images. Emailing parents and asking students to bring in magazines is very helpful. I put out a box or other container to collect the magazines as they come in. Be sure to preview donated magazines before making them available to students though- one year I got a donation of the Sports Illustrated Swimsuit Issue! Once you have have a good collection of magazines, some cardstock paper, glue, and scissors (optional), you are ready to begin making collages.

With all of the materials available to students, I let them peruse the magazines to look for images that reflect their personalities and preferences. They find images of things they like to do, their favorite foods, pop culture of interest to them, places they have been or dream of traveling to, and other favorite things.

Students may rip or cut images, and I suggest to them that ripping the paper creates a nice transition between two images in a collage. Students sometimes choose to add words and phrases that they like. They “sign” their collages by spelling their names using letters found in the magazine text. 

Once the collages are done, give them time to dry before putting them in a pile so that they don’t stick together. I have done this activity right before a prep period so that collages can be left on student desks, or I dedicate a separate space for them to dry. Be aware that some students will finish relatively quickly, while others will want more time. I have early finishers assist peers in finding images they are looking for. (I also frequently make announcements to the class when a student is looking for a particular image so that everyone can help look for it.) For those who need more time, I provide the materials during a study hall or student free time.

Displaying student collages is a nice way to decorate the classroom and make students feel more at home in the space. The collages spark conversations between students about the images and words they chose, encouraging them to learn more about one another. There are many possible ways to display the collages, and after trying several different methods, I settled on hanging them from a wire placed high on the classroom wall and keeping them on display for the entire school year. I was lucky to have help with this from my husband Parthiv and art teacher Andrew, who both graciously assisted with installing the wires along with hooks to support the wires. Once this was done, I hung the collages using clothespins.

It was fun putting my students' collages on display, knowing that they would enjoy seeing their work when they entered the room. Thanks to the simple artwork my students created, my classroom always had a bit of decoration with a personal touch. 

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Summertime Science in the Garden: Pollination

Bumblebee visiting gayfeather flowers in my dad's garden in Maine

Summer is a great season to spend time in a garden, and you often receive a little science lesson in the process. I enjoy watching various pollinators at work as they visit flowers. One of my favorites is the bumblebee, which is able to access pollen unavailable to other pollinators. Its secret is buzzing at a specific frequency that causes the flower's anthers to open and release pollen. (To learn more about buzz pollination, see the link at the end of this post to a Science Friday video on this topic.)

I learned about the importance of pollinators the hard way one year when my zucchini plants produced lots of flowers but no zucchini! I discovered that zucchini and other squash flowers are monoecious, meaning they have separate male and female flowers on the same plant. They can't self-pollinate, like some perfect flowers do, but instead rely on pollinators for the flowers to develop into fruits, the zucchini. Pollinators carry pollen from the anthers of a male flower to the stigma of a female flower. You can see these flower parts in the photos below, taken in my plot in the Juniper-Front Community Garden in San Diego.

Male squash flower with pollen-covered anther in the center

Female flower with stigma in the center

Fellow gardeners suggested that I plant some flowers to attract pollinators, and this has been very helpful. I learned that humans can serve as pollinators, too! This is a fun activity to do with kids. To hand pollinate a zucchini or other squash flower, remove the petals from a male squash blossom, and rub its anthers on the stigma of a female flower. One male flower can be used to pollinate multiple female flowers. 

Female blossom- note ovary below petals

Three days later: ovary developing into fruit

Male flower- note absence of ovary below petals

Once the flower has been pollinated, the pollen forms a tube that travels from the stigma down through the style to fertilize the ovules at the base of the pistil, triggering the development of the zucchini fruit. I now use this trick to pollinate my zucchini and spaghetti squash flowers with great success! 

If you enjoy watching pollinators and think you might be interested in helping collect data on pollinators in your area, you can learn about a citizen science project called The Great Sunflower Project in this blog post:

Get Outdoors with Citizen Science! The Great Sunflower Project

To learn more about buzz pollination, check out this Science Friday video:

Science Friday Video on Buzz Pollination

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Trashion Show: Weaving Art into Lessons on Human Impact and Sustainability

The most fun project that I do with my students is by far our annual Trashion Show, a project that compliments the NGSS standards related to human impact. As students learn about sustainability, they are challenged to repurpose landfill-bound textiles and other materials to create new outfits and costumes. We do this project at the end of the school year, and I’ve found that it’s a great way to keep students engaged and motivated even with summer vacation on the horizon. Students work with a purpose: to use their creativity to put on a great show! Guiding students in creating the Trashion Show keeps me motivated, too! As their teacher, I love seeing students' individuality on display in the outfits they create and the other work they do. 

Well before we begin working on the Trashion Show, I start soliciting donations of used textiles. Over spring break, I send out an email asking families to save items for us while doing their spring cleaning. This year my dad was the face of my donation campaign. I used a photo of him holding a very well-loved and worn t-shirt that he was donating to us with the subject line, “Do You Dress Like My Dad?” 

Once students begin working, they may have specific used materials that they are seeking, so I send additional emails with a list of their desired trash. My general rule for creating Trashion Show pieces is that we shouldn’t create more trash than we started with, so students need to design outfits that can be taken apart into recyclable pieces at the end of the show. (The exception is for used materials that can't be recycled.)

Not all students want to be designers and create outfits, but there are other important jobs that need to be done. A DJ is needed to work with designers and models to select songs to play. The marketing director works on advertising by drafting emails to send to teachers and families and fliers to post in the school. There are typically two MCs who introduce and close the Trashion Show and read descriptions of the outfits as they are being modeled. Speech writers work with MCs on the script and assist designers with descriptions when needed. 

The teacher acts as a project manager, keeping the work flow in motion by guiding students who finish their tasks to find work that needs to be done in another area. As students are in the midst of creating their outfits and costumes, I provide them with opportunities to showcase their works-in-progress and plans for the outfit. The goal of sharing their work helps students stay focused, and I can easily see the development of all of the pieces. 

Model and Designer of "Childhood Dreams"

My dad's old shirt made new again!

The Trashion Show is a project I lead with the 6th-grade class, but other members of the school community are drawn in as models and later as our audience. Involving kindergarteners and other younger children as models is always a crowd pleaser, and I often have my daughter model an outfit that I have made. The model who always got the most applause though was our former principal, Phil Beaumont, who is a natural (and professional) performer! 

Holding a Trashion Show is a nice way to bring the entire school community together and have some fun while weaving art into science lessons.

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UCSD Engineering Project for San Diego Students Grades 4 and 6

 

If you teach fourth or sixth grade in San Diego, you might be interested in having your students participate in the University of California San Diego's Seismic Outreach program. This hands-on project follows the engineering design process used in the Next Generation Science Standards as students gain experience creating earthquake-resistant structures. Another great part of the program is the exposure your students get to engineering students at UCSD and campus life. 

The project begins with a visit from UCSD engineering students, who give a presentation on earthquake-resistant building design. Students then work on teams to create specified building structures made out of K'NEX pieces and test them either by shaking them manually or placing them on a homemade shake table (seen in photo above). UCSD provided me with directions for how to build one using materials you can get at a hardware store.

When building and testing specified structures, each team is given a variable to test, such as where to place bracing or whether to make the first story taller or shorter. Teams present their findings to the class, take notes on their peers' presentations, and then use this information in the design of their final building. Following the engineering design process, students build their models, test them on the shake table, and refine their design.

Students work on their test structures and buildings for a few weeks, so it helps to designate a space in the classroom for storage. 

The most exciting- or maybe nerve-racking- part of the program when students present their buildings to be tested on an electric mini shake table. This is done with a field trip to the UCSD campus or sometimes a second visit by UCSD students. My students look forward to the event but are also nervous about how their buildings will perform! Many buildings do break on the shake table, so I prepare my students by letting them know that it's the job of the UCSD students to try to break their buildings, and they are experts at doing this. Having buildings break is just part of the process, and when UCSD students have their own structures tested, they routinely break, too!

The Seismic Outreach program touches on NGSS standards beyond engineering. Students are introduced to waves by learning about the seismic waves that cause earthquakes. Earthquakes teach students about tectonic plate movement. Before starting the Seismic Outreach project, I lead students in doing activities related to the movement of tectonic plates and the location of fossil finds, hitting other NGSS standards.

If you are interested in learning more about the Seismic Outreach program at UCSD, follow this link:

https://scse.ucsd.edu/seismic-outreach.html

If you would like to explore another engineering project for middle school students, see my blog post about Future City Competition:

Students Explore Engineering and Sustainability through the Future City Competition

For a low-prep team building activity, follow this link to a blogpost on Venn diagrams:

Classroom Icebreaker / Getting to Know You Activity: Venn Diagrams

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