On 10/4 the 2nd and 3rd graders played more with geometry and were introduced to the concept of tessellation. Tessellating a flat surface is the tiling of a plane using one or more geometric shapes with no overlaps and no gaps. In math, tessellations can involve higher dimensions and a variety of geometric shapes. A periodic tiling has a repeating pattern - think of the tiles on your kitchen floor.
During the week of Sept. 29, 2nd, 3rd, 4th, and 5th graders got to explore more with projectiles in motion and how potential energy is converted into kinetic energy. We reviewed the principal of inertia initially analyzed by the great Galileo and discussed the difference of potential energy versus kinetic energy. The path of any projectile is a "parabola" and the force of gravity is 9.8 meters per second. How is this important when building our experiments? It's important if you want to build a machine that will launch something far and high - it's also important in a little healthy competition between the different teams! We discussed where the potential energy could be stored in both the confetti launcher and the catapult.
When doing the catapult experiment, we discussed how launching an object at a 45 degree angle will yield the most horizontal distance and graphed it out an XY axis so the students and further understand and visualize the "parabola." We also tested out what would happen if we were to launch from a 30 degree angle vs a 60 degree angle. As theorized, the projectile would be traveling the same horizontal distance! We also watched a short video of the great pumpkin lauch taking place at this time of the year across many States and watched how others have created their catapults to launch pumpkins over 300ft! The students loved experimenting with and designing their personal confetti launcher and catapult! These two projects really demonstrated the relationship between force and speed. We shifted gears this week and explored a fun geometry project. We reviewed symmetry and bilateral (line) symmetry and discussed congruent shapes. Then we launched into a project to rotate and reflect 2D shapes into 3D creations! The task was to first draw 1/2 of a shape onto a cardboard that they wanted to see come alive into a 3D object (with one requirement of having one straight side - which will eventually become our axis of rotation). About half of the class got this right away and others took a bit of time to get their mind around what this should look like. It's never as easy as it looks. The trick is to go big and have simple clean lines. A mash-up of geometric shapes work best. Then we cut out our stencil and traced our model onto 8 more sheets of paper to give our flat shapes life! The 3rd graders especially loved this creative and artistic project and made 2 to 3 each. Check out their creations below!
Water was the theme for last Thursday's challenge for the 2nd and 3rd graders. They got their hands dirty in making a working water filter (which was review for some folks who were in STRETCH last year) and they had to save a village from a flash flood (very appropriate for our Maui weather!). There was also the challenge of working with new team members and being open to accepting different opinions and testing out new ideas. I'm also a big advocate for the soft-skills that they gleam from our engineering challenges - being able to work with team members is key.
Most teams got the water filter part fairly quickly and dirty yellow sandy water became almost clear and particle-free water. Building a dam to prevent a flash flood proved to be more challenging. I am definitely super impressed with how much perseverance the students had to get it right - no matter how many tries it takes. I'm truly proud of them for not necessarily worrying about winning the challenge but being determined to get the project working properly. Bravo to my 2nd and 3rd graders! Today we learned about earthquakes and what causes them. We reviewed the lithosphere, mantel, outer core, and inner core and discussed how tectonic plates move and locations of fault zones. Demonstrations were made of S Waves, P Waves, and we reviewed how a seismograph works and what it means to be near the 'epicenter' of an earthquake. The 2nd and 3rd graders got to build an earthquake-safe structure out of wooden sticks and rubber band. The challenge was to make a building 12" tall and withstand 20 shakes on the earthquake simulator. The most successful structures utilize our great friend - the triangle! The pyramids of Egypt served as a great source of inspiration. This engineering challenge was definitely harder than it looks but the students made an awesome effort!
Newton's Third Law of Motion: for every action, there is an equal but opposite reaction. Enter the balloon-powered car! This week 4th and 5th graders were given a challenge to build a car with recycled materials (cardboard boxes, bottle caps, popsicle sticks, skewers, etc.) and with a 12" balloon as the car's propulsion system. As the balloon is being blown up, the potential energy of the car is stored in the expanding elastic and as air flows out of the balloon (from the attached straws), the potential energy is converted to kinetic energy. The moving balloon car is using kinetic energy. Easy right? Not exactly. While in theory this seems simple, it takes quite a lot of trial and error on designing the axel/wheels to make the balloon cars go straight. And then there is speed - how much is too much material that will weigh the cars down and stop it from moving? It's all a lesson in getting to that right balance and tweaking and re-tweaking with different car bodies. Some of the students experimented with box cars while others experimented with empty bottles. The winning team was able to get their car to travel 11'!
Our daily lives are made easy by simple machines and the pulley is a prime example that helps us lift heavy weights. The 4th and 5th graders had a challenge last Wednesday to build a pulley system out of only paper towel rolls, string, a plastic cup and tape. The system has to be 16 inches tall, free standing, and pull up 75 grams without collapsing. The students got super creative in creating their pulleys and cranks - in fact, some of these structures are still proudly standing in our classroom!
Yesterday 2nd and 3rd graders had the chance to rescue a teddy bear from the bottom of a well. Their challenge was to build a rescue device (with only hollow plastic connectors and a long string) that could reach into the bottom of the well and extract the teddy bear successfully. The teams that kept the challenge simple had the best outcome whereas the groups that tried to use all the materials and build a claw type device had more difficulties. We even had a team attempt a suction/vacuum type of device! After many iterations of redesign, all teams successfully rescued the toy bear!
The 4th and 5th graders kicked off the year with a cool lava lamp experiment and made their own 'take-home' mini lava lamps! Lava lamps came into popularity in the 1960's but what is the science behind these groovy contraptions? The answer lies in density. How compact is a substance? How much of it fits in a certain amount of space? The students were quick to catch on that water is more dense than oil causing it to sink to the bottom of a beaker. Students also hypothesized that when heated, the molecules expand and rise so temperature affects density as well. The students got into teams of 4 and made a group lava lamp using a beaker of oil, water, food coloring and instead of the light bulb at the bottom of real lava lamps, we used a tablet of Alka Seltzer to fuel our lamps! During the experiment though, students could not resist the temptation to shake the mixture but soon learned about polarity. The water molecules have polarity (negatively charged Oxygen atom at the bottom and 2 positively charged Hydrogen atoms at the top) and vegetable oil is non-polar, the two would never mix and are thus, immiscible. Check out the fun pictures below of our budding chemists: |
AuthorsMrs. Shim and her STRETCH students Archives
May 2015
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