Force

Lately we've been working with three types of force: gravity, friction, and magnetism. We started an investigation in which we made three pendulums of different lengths. We timed how long each pendulum took to make 10 swings, then looked at our pattern. For our pendulum with a string 10cm long, it took 5 seconds to swing 10 times. For our pendulum with a string of 20cm long, it took 6 seconds. Our pendulum with a string of 30cm long took 7 seconds to swing 10 times. We then predicted how long it would take a pendulum with strings of 40cm and 50cm to swing 10 times.

We discussed the forces involved in our experiment. We talked about the gravitational pull, which was responsible for making our pendulum fall. We also discussed the friction of the air rubbing against the string, which was responsible for slowing down the pendulum to an eventual stop. There is also friction found in the string rubbing against the pencil. This, too, helps slow our pendulum's swing.

Insulators vs. Conductors

Our journal sheet for this activity

Using a door hinge as a conductor

Today we explored insulators and conductors. The kids were given a baggy of 7 items - a binder clip, a dime, a penny, a Popsicle stick, an eraser, a pen, and a brad. They were also given the circuit supplies of a battery, wire, and a wire with a light bulb attached.

They were to test the items to determine if they were insulators or conductors. They did this by adding them to their circuits and observing whether or not they light came on. When they finished, they were to go around the room and find other things to test. Here are some pictures of the items they tested.

Using a metal letter as a conductor

Using a metal desk leg as a conductor

Figuring out the eraser is an insulator

Electrical Circuits

In science we've begun to explore electrical circuits, and what they must have in order to be complete. The kids were handed a battery, wire, and another wire with a light bulb attached, then they were told to make the bulb turn on. That's the most direction they were given.

All groups were eventually successful in turning on the light. It's always fun to hear their conversations as they make their cases for why their way will be successful. Most groups figured out they didn't even need the extra wire!

 After they finished, we discussed what parts an electrical circuit needs to be complete. It must have a power source, conductor, something that needs the power, then finally the circuit must be closed. We also discussed the idea that while circuits don't have to have an insulator on the wires, it's probably a great idea. ;) 

Circuit Journal Entry

Right Angles

As we begin to explore right angles, we first discuss the degrees involved. From our prior knowledge regarding quadrilaterals, we know they are made up of 360 degrees. We further the discussion by looking at a quadrilateral that is made up of four right angles. If there are four, and they're all equal, they must measure 90 degrees.

After this discussion, we decide how we might find right angles within a shape. This leads us to using the edge of an index card. I find this helps those kiddos who struggle a bit more with spatial concepts.

After lots of playing around with shapes and labeling their angles, we move on to combining polygons to make right angles. This is a bit more challenging. This always leads to great discussion about what size angles might we pick when trying to make a right angles. The kids can see they need to be looking for angles smaller than 90 degrees, otherwise their angles are going to be too large. As the kids found angle combinations that worked, they recorded them in their journals.

Separating Mixtures and Solutions...Again

Today we separated mixtures of sand and water, sugar and water, and salt and water. We first mixed the materials, then predicted what would happen when we evaporated the water. As a class, we decided the sugar and water would all evaporate because the sugar had dissolved into the water. We hypothesized the sand would remain from the sand and water mixture, and the salt would remain from the salt and water mixture. After the water had all evaporated, we examined what was left. The students were pretty surprised by the results from the sugar. The sugar had not evaporated. In fact, the sugar and water had created a thick syrup. Sugar crystals actually started to form on the sides and top of the beaker after the syrup sat for a while.

Separating Mixtures and Solutions - Beach in a Bucket

This week we worked on ways to separate mixtures and solutions. One of the labs we did was a beach in a bucket. The kids first made their beaches by combining in a bucket 1 cup of sand, 2 tablespoons of salt, 1 cup of gravel, 4 larger rocks, and 1 cup of water. After we mixed all the ingredients together, we discussed what part of our beach was the mixture (sand, rocks, gravel) and what part was the solution (salt and water.)  We began separating the rocks with a spoon, then we used a sieve to separate the gravel. This left our sand, water, and salt. Many of the kids initially thought sand would be part of the solution because the sand would dissolve in the water. We proved this was not the case by letting the sand, salt, and water sit overnight. When we returned the next morning, the sand had settled to the bottom of our beaker.

Separating rocks from our beach

Separating gravel

What is left after taking out gravel

We used a colander lined with a paper towel to separate our sand from our water and salt.

Separating sand

Finally, we were left with our solution, which we knew was going to be much more difficult to separate. After some discussion, the kids decided we needed to use a hot plate to evaporate the water. Some kids thought the salt would be left behind, but some were sure it would also evaporate because it had dissolved in the water. We used our hot plate to boil the water for a while, and when we returned, we found a cup full of dry salt!

The salt left in the beaker

Separating water and salt

Separating Mixtures and Solutions

This week we created some mixtures and examined ways to separate them. We began with a food coloring and water mixture and also a sugar and water mixture. With both of these mixtures, one of the materials completely dissolved, thereby giving us a solution (special kind of mixture where one thing dissolves into another).

Next we mixed sand and water. No matter how much we tried, we couldn't get the sand to dissolve in the water. We determined this was a mixture because the sand didn't dissolve. When trying to separate the two materials, we first let the sand settle to the bottom, then we used a coffee filter to filter the sand from the water.

Our next mixture was sand and gravel. When mixed, the two materials retained their physical properties. We simply had to use a sieve to separate the two materials.

Finally, we combined iron filings and pepper. The students used a magnet to separate these two materials. This was the students' favorite mixture to separate! The way the iron filings stuck to the magnet was pretty cool!