Acceleration is the change in velocity over time. Velocity changes when speed, direction, or both changes. Anyone can build a simple accelerometer. The video below shows how to build an accelerometer and how to use it.
Teaching how the eyeball works usually involves showing diagrams of the eyeball and showing how light passes through the lens. Science teachers can also use Jello to make lenses that will show laser light refraction. I tried that and had disastrous results. I started to play around with mixing baby powder (mostly cornstarch) with red food coloring and water. I was quite pleased with the results. Go ahead and watch the video below to see what happens.
The idea for this demo came from Steve Spangler Science. In his post he states:
Tonic water might not be your first choice for a beverage, but it's the secret ingredient you'll need to make a glowing geyser. It turns out that tonic water will glow under a black light because tonic water contains quinine, a chemical that was originally added to tonic water to help fight off malaria in places like India and Africa. While the tonic water we drink today only contains a small amount of quinine, it's still enough to make your drink glow under black light.
Instead of using mentos to make a glowing gyser, I decided to do a Hero's fountain version. You can get a simple apparatus from teachersource.com that fits into 2 2L bottles. Where in your curriculum can you fit this? In eighth grade science we cover properites of matter such as denisty, phase at room temperature, color, flame color, smell, texture, etc. Some chemicals can be identified from the ability to fluoresce when exposed to uv light. I would maybe do this with a fountain of regular water and one with tonic water and then ask the students if the same chemical is in each founatin.
The alkali metals are highly reactive since they have one valence electron. One of those metals is sodium. It needs to give up one electron to become stable. When a cubic centimeter sized piece of sodium is placed into water, a vigorous chemical reaction occurs in which sodium hydroxide (NaOH) and hydrogen gas is produced. Wikipedia provides an excellent description of what happens during the reaction.
Sodium reacts exothermically with water: small pea-sized pieces will swim around the surface of the water until they are consumed by it, whereas large pieces will explode. While sodium metal reacts with water, you can observe that the sodium piece melts with the heat of the reaction to form a perfect sphere shape if the reacting sodium is small enough. The reaction with water produces very caustic sodium hydroxide and highly flammable hydrogen gas. In any case these are considered an extreme hazard and will cause severe skin and eye injury.
In the video below a small pea sized piece of sodium is placed into water. It does ignite and explode. To avoid an explosion ice water should be used. To avoid ignition a safer method can be used in which a layer of mineral oil is placed on top of the water. The mineral doesn’t react with the sodium and prevents ignition.
For a safer sodium demo, fill a large graduated cylinder with and equal portion of water and mineral oil. The mineral oil will be on top. When sodium metal is dropped into the cylinder it won’t react with the mineral oil and when it touches the surface of the water, it reacts briefly to produce hydrogen gas bubbles, thus causing it to rise back up into the mineral oil.
One of my goals entering this new school year is to improve the teacher/parent relationship. After 15 years of teaching I have met many wonderful supporting parents, but I have to admit my view on parents has been tarnished by the few less than capable parents that I have encountered during that time. So I here is what I will pledge to all parents this coming school year.
- I will acknowledge that you know your son/daughter better than I do. I only have your child for 45 min a day. Granted, I see them in a different social context that you do, you actually have spent 11-12 years with them and you probably have more in depth knowledge of what they are like. I will use your insight to better help your son/daughter.
- As a student you have experienced many years of the education system and it may have been a negative and or positive experience and many of your fears and expectations are based on that. What you need the most is all the facts and information. The more information I can give you, the better you can make decisions. I will give you all the information about policies, procedures, standards, testing, grading, resources about my class and the school.
- I will contact you more. I will give you the positive information and the negative information, preferably in that order. I will do this mostly by email, since it more efficient than phone calls and more personable than the robotic phone dialing system that our school uses. Too often what you tell students during the day is not communicated on to the parent. I need to bridge that communication gap.
- I will respond to emails in a timely manner. During a busy school day it's easy to forget that you had to respond to that parent's email. On the flip side I will pledge to not respond quickly to a negative parent email. There needs to be a cooling off period, so that I can calmly and rationally respond to a hostile email. Sometimes it requires a good night's sleep and then cooler heads will prevail.
- I will presume positive intent. I will not prejudge the parent when the son/daughter does not meet expectations. Parents, you have the most challenging job in the world and you want only what is best for your child. I always need to remember that, and you are probably 10 times more frustrated with the situation than the teacher is.
I'm sure as the year goes on that I will have to adjust my pledge, but I think that this will be a good start and hopefully will lead to some good learning.