Thursday, March 22, 2012

Physics: Quiz boards Day 2

This week the kids finished their quizboards - hopefully by now you've seen them, played with them, and hopefully not broken them! This was NOT an easy project. It took a lot of patience and attention to detail, checking and rechecking connections in the circuits, but in the end it paid off. "Operation's" got nothing on these quizboards.

Biology: Birds and the Beans

This week we took what we learned about genetics one step further. We asked the question: if individuals with one version of a trait have an advantage over individuals with other versions of the trait, what happens to the distribution of this trait in the population over time?

To understand this concept, we carried out the following exercise. We started off with 50 red beans and 50 white beans, representing the parent generation. The beans were spread out over the white floor. A kid/bird from each group would hunt for 75 beans, and then the 25 remaining survivors would reproduce, having 3 offspring, each one the same color as the parent. The kids repeated the simulation 2 more times, and then observed the long-term effects of living in this particular environment on the frequency of red and white beans in the population.

Over time, the frequency of red and white beans changed, with white beans outnumbering reds. Put another way, the population evolved. The white environment gave white beans an advantage in helping them camouflage, so white beans were in effect "selected by nature" (that's why they call it natural selection). Whites out-performed reds, causing them to be more successful, which in biology means having more baby beans, and over time the frequency of each trait changed. We wrapped up by discussing how things may have turned out differently if our bean population was living on the red sidewalk or the green grass.

Sunday, March 18, 2012

Physics: Quiz board

This week the kids started to build quizboards.

What's a quizboard? A quizboard is a game in which you try to match up questions with the correct answers. If you succeed, a light bulb turns on, and if you get the question wrong, nothing happens.

Interesting child psychology fact: When I do this activity, it is ALWAYS the case that kids suggest adding features to the quizboard that will punish players with a beep or even a shock for wrong answers. Go figure...

As of last week the kids have written their quizzes and started building and insulating the wires that will connect questions and their respective answers. Next time we meet they will complete their quizboards and bring them home.

General Science: Case of the stolen skull

There were no two ways about it. I took her call 'cause I needed the money. The case was dirtier than a first grader's backpack and twice as heavy. The broad that hired me told me a couple a thugs took her skull, and I ain't talking about the one sitting on her shoulders neither. Seems she's into studying bones, and a couple of years backs some students gave her a horse skull they found. Now it was missing, and the only clues I had were four sets of prints and a pile of white powder.

Called in a favor with a buddy of mine downtown and he ran the prints and came up with a list of suspects with records so clean you could eat off of them. An English teacher, Devra Lehman, Asaf, the owner of the local toy store, the damsel in distress herself, Rebecca Perlin, and her husband, Danny Sadinoff. Each one had his own strange connection to a specific white powder: Devra to corn starch, Asaf to sugar, Danny to baking soda, and Rebecca to salt.

I let the boys in the lab take a crack at it. They tested the powder with more chemicals than you'd find in a package of Osem soup nuts. Then they looked at it under the microscope and checked if in solution it could conduct electricity.
They compared the results to some similar cases they had a while back, and the answer was clear as day.

That science teacher must have thought I was some chump – turned out she was right. It was her and that other broad, the English teacher. One was in it for the thrill, the other for the spelling mistakes. Me, I had bigger fish to fry.

Monday, March 12, 2012

Biology: Genetics of Blood Types

This week we continued learning about genetics. Once again we carried out a simulation. However, there were a couple key differences from last week:

  • Last week "parents" produced 1 child with a lot of different traits, and this week "parents" produced MANY kids, focusing only on a single trait.
  • Last week we looked at made up traits, such as star- vs blast-shaped eyes, while this week we looked at a genuine example: ABO blood types in human genetics.
  • Because we had such a large sample size of offspring, we were able to compare the distribution of the different genotypes and phenotypes to what we would predict based on chance alone.

Wednesday, March 7, 2012

Biology: Genetics with a smile

This week the kids carried out a simulation in which they explored how traits are passed down from one generation to the next in the strange but cheerful species, commonly known as "Smileys." The kids flipped coins to see which genes the Smileys would pass on to their offspring. Afterward we compared and contrasted Smiley and human patterns of inheritance. The following statements hold true for both species:
  • Each individual caries 2 versions of each trait, one from mom and one from dad.
  • Each individual passes 1 version of each trait to an offspring.
  • The offspring's phenotype (what he looks like) is the combined result of the 2 versions he got from mom and dad - sometimes, but not always following the rules of dominance.

Thursday, March 1, 2012

General Science: Chemistry in a bag

This week the kids carried out a really complicated lab. They mixed 4 different materials (calcium chloride, sodium bicarbonate, water, and phenol red) in a plastic bag. The materials that were liquids weren't added directly. Instead we first poured them into plastic cups, which themselves were carefully placed in the bag. Why all the extra steps? This allowed us to measure the mass of the whole business BEFORE and AFTER the chemical reaction took place. The kids were pretty surprised to find very little if any change. That's conservation of mass for ya!

As the materials combined the kids observed and recorded the many chemical changes that took place including: bubbles, color changes, and temperature changes. While all these changes were pretty cool, the fact we had combined so many different things at once made it tough to know what was really going on. Part 2 of the lab was breaking down the initial experiment into every possible combination of ingredients, carrying them out, and analyzing the results. By the end the kids new exactly which combo was responsible for each change.

Physics: Circuits are cool!

This week's experiment was originally called: "Experimenting with different kinds of circuits," but about 5 minutes into it, the kids decided to change the name to "Circuits are cool." We did, and they are. The kids learned about the parts of a circuit: battery, load, and wires, and they were challenged to build circuits that could turn on light, motors, and annoying beeping machines. What's that saying...necessity is the mother of invention? Following their success with the annoying beeping machines, we introduced the concept of switches. Ah....sweet silence.

Physics: Static Electricity

Believe it or not?!

  • A balloon sticks to the wall.
  • A stream of water bends.
  • Two strips of plastic torn from a bag held side by side sway in opposite directions from each other.

Like most magic tricks, what you see is never the whole story. What causes materials to be attracted to or repelled from other materials is a phenomenon called static electricity, an imbalance in charges. This week we tried to understand a little more about how electricity works at the atomic level. To do so we reviewed the atom's basic structure, including positively charged protons, neutral neutrons, and most important for our topic, negatively charged electrons. We talked about how atoms that gain or lose or electrons becomes charged, and are then attracted to oppositely charged materials.

Biology: Owl Pellets

Over the last 2 weeks we dissected owl pellets. Owls are really interesting for many reasons.

  • Owls can turn their heads as much as 270 degrees.
  • They're nocturnal.
  • Many species of owls have special flight feathers adapted for silent flight.

and my personal favorite, although not for the fainted-hearted...

  • They consume their prey whole, and then regurgitate the undigested fur and bones in a compact pellet that can be dissected.
Still there?  Well, if you can stomach the dissection, (Truth be told, it's more of a in your head gross than an actual gross) this is just about one of the coolest labs you can do!

The first step was to remove all the bones from the pellet.  Next the kids classified the bones, putting each type in a different compartment of an egg carton (is there any craft or science project that isn't vastly improved by the use of egg cartons?!).  Finally the kids used pictures of intact skeletons to identify and reconstruct the prey skeletons they had discovered.  Awesome!

General Science: Growing Crystals

This week we continued our investigations of solutions by making and examining crystals under the microscope. First we made saturated solutions of salt, copper sulfate, and borax. Then we placed a drop of each on a microscope slide, put them outside and waited for them to evaporate, and then used a microscope to look at the crystals that remained. We are also trying to grow some larger crystals. We'll see how they turn out next week...
One week later...
The good news is, Israel got a lot of rain this week. Great for growing crops, bad for growing crystals. We were hoping for our super saturated solutions (say that 5 times fast!) to evaporate, leaving behind beautiful crystals. Not likely to happen in the pouring rain. Next year we'll try this experiment in the late spring. In any case here's a picture of what you get when you SUCCESSFULLY grow large sugar crystals.