7th grade

Zebrafish: Day 5

By Shirin K and Molly C-U, 7th grade (photos by Molly C-U)

On our final day with the zebrafish, all of the embryos hatched into larva! Curiously, out of the 101 zebrafish larvae in our entire class, all of them were wildtype, meaning that they developed pigment. Tracy Nelson from Penn returned to teach us why. The male, who was albino, was homozygous for the recessive allele (ww). (A gene codes for a particular trait, like pigment. An allele is a particularly variation of a gene, such as “no pigment” or albino.) The male evidently mated only with the wildtype female (not the albino female), whose genetic make-up was homozygous for the dominant allele (WW). Together, their children were heterozygous (different) for pigment, meaning that they carried one dominant allele (W) from their mother and one recessive allele (w) from their father. When this happens, the dominant allele takes over and is expressed in the phenotype. This made the larvae have the outward appearance of a wildtype zebrafish. Overall, we had a wonderful time studying the zebrafish this week.

Day 2: Heritage Farm

By Molly C-U, 7th grade

On our class's second trip to Heritage Farm, we worked on planting.  (If you haven't read about Week 1, here is the link.) Adrian said the last frost had been that past Saturday evening, so that since then they had been frantically planting as many crops as possible.

Our job was to plant several hundred chives, red and green lettuce, and kale.  A few people dug the holes for the plants with a rolling tool that Adrian had created. One group carried plants over from the greenhouse, while another soaked them in nutrient-rich water to make them healthier and then dropped them into the holes. The third group gently split the roots and covered them with dirt. No one was afraid to get their hands dirty, and everyone worked hard. Adrian said that the work that took us three hours would have taken the four of their staff about two days working as hard as they could.

Because we got to eat lunch in the greenhouses again, we also got to see how things had changed from the week before. The crops had grown so much, and we could also see changes in things we didn’t work on, like the fruit trees and other crops.

We look forward to seeing our crops next week!  

Zebrafish: Day 2

By Molly C-U, 7th grade

The second day of the 7th grade's zebrafish lab started with another talk by Tracy Nelson from Penn. She described the different stages of embryo development and the anatomy. For example, we learned that the chorion was the protective shell around the embryo, and the yolk was its food source. We also learned that for the first few hours after fertilization the embryo consists of stem cells clustered around the yolk. These cells are later assigned to jobs like pigment cells, skin cells, and blood cells. Tracy went on to show us how we were to remove the male and female zebrafish from the tank while leaving the embryos, and then how to move the embryos into a petri dish that we could observe under a microscope.

After carefully draining the water, we transferred the fertilized eggs and started observing. In my group’s dish there were 14 embryos, all about the same “age” (14-18 hours post fertilization (hpf)). They had no pigment and were still curled almost all the way around the yolk. None of the groups had pigmented embryos yet, but some were farther along in their development. A few groups had unviable embryos, meaning they had the chorion, but the actual embryo was dark, small, and had stopped developing. Tracy explained that it was typical for a small percentage of offspring to become unviable in these early stages.

I still don’t know if our zebrafish will turn out to be more wildtype or more albino, and I’m very curious. I also wonder if any of my group’s embryos will be unviable, though we haven’t found any yet.

Zebrafish 2016: Day 1

By Molly C., 7th grade

In 7th grade we started our zebrafish Lab. The point of the lab is to teach us about zebrafish and introduce us to the genetics of inheritance. Tracy Nelson from Penn’s Institute of Regenerative Medicine explained why zebrafish are a model organism in genetic research. For example, zebrafish are 70-75% genetically similar to humans, they develop diseases like us, such as cancer; they produce many offspring (which produces a lot of data), they have clear embryos, and are cheap to care for. In addition, their embryos develop and hatch into larva within a few days, so we can conduct the experiment in just one week.

After reviewing the procedure for setting up mating tanks, each group was given three zebrafish: one male albino, one female albino, and one female wildtype. 

Seeds of Change "a-Maze"

Yesterday was the grand finale of the 7th grade's Seeds of Change unit. Visitors had the opportunity to see the products of student research from the past month, set within a thematic presentation space that transformed their classroom areas into a mysterious maze of ideas and intrigue. 

Students researched seeds of change of the past, present, and future. Some of their topics were

  • comparing the sizes of fast food drinks in america and other countries (ex. what constitutes a "large" in some countries is the same size as a "small" in america)
  • how our "war on drugs" perpetuates the cycle of addiction
  • the zika epidemic
  • the vaccine controversy -- to vaccinate or not
  • the pros and cons of modern and ancient farming methods
  • the negative impact of artificial selection in breeding dogs
  • the role of the horse in major military battles since Genghis Khan
  • the three ingredients needed for major medical breakthroughs
  • the environmental and health risks of factory farming

Here are some photos by TPS parent Kate Riccardi.

7th Grade Tech Spotlights

by Ella W., 7th grade

In the weeks before winter break, the 7th grade began meeting all together with tech integrator Matt Murray to discuss appropriate and useful ways that we can learn to use our electronics. Here are summaries of two of the tech spotlights.

SPOTLIGHT: Website Reliability

We started off by discussing whether certain websites were reliable or not reliable to use. Matt introduced six criteria to help our assessment:

Criteria Used to Determine Reliable/Unreliable Websites

  • Author (of site and article) -- Does the author have strong credentials?
  • Publisher (.edu vs .com) -- Is this an educational or commercial site?
  • Purpose of site -- Are you seeing advertisements? What could that tell you?
  • Intended audience -- What does the tone/voice of the site tell you about its intended reader?
  • Quality: Citations, hyperlinks, timeliness -- Is the information posted reliable and current? Can you tell where the information is from?
  • Does the information make sense to you? -- It’s often good to “trust your gut”; if something doesn’t seem quite right, keep researching.

SPOTLIGHT: Conscientious Connectivity: Social Media Use and & Your Digital Footprint

In this spotlight, Matt talked to us about applying to high school and college, and whether we want those schools to see the pictures and posts of us on the Internet.

Permanence of the Internet Memory Hole: The Internet has a very good memory.  It keeps things that we think are deleted or forgotten about.  Sometimes that is because of Web Page Duplications.  Companies can make millions of dollars off of your information that is not actually deleted.  “Deleted” isn’t really deleted.  There are websites dedicated to storing every single webpage ever created.  Also, any one of us  could be the subject of surveillance at any point because of organizations such as the National Security Agency (NSA). Companies can also change privacy settings at any point without you knowing.  We all have unique IP addresses that can track what we are doing.  Everything you do on a service provider is saved by them.  Online Disinhibition Effect is when people think that they are anonymous, but really that is a mistake.  If you are hiding behind a username, your secret is actually not safe.

There are so many beneficial ways to use electronics. We can leverage social media to be a better person.  Here are some tips:

  • Post positive things instead of negative.
  • Act on the Internet like the world is watching (because it is).  
  • You should never post or say anything online that you don’t want other people to see.
  • Practice digital empathy. Imagine being the person receiving something negative online.
  • Be conscientious! Cyber-bullying can affect lives everywhere, even if you don't realize it.
  • Most importantly, before you use Social Media…THINK!
    • T -- Is it True?
    • H -- Is it Helpful?
    • I -- Is it Inspiring?
    • N -- Is it Nice?
    • K -- Is it Kind?