ALK means that the chemical is alkaline which means the opposite of acid but just as dangerous. The word "alkaline" comes from a plant that grows next to salty lakes or oceans. In Arabic, it's called "Al Kali" or the saltwort plant. The ashes of this plant neutralizes acids. That is why chemicals that neutralize acids are called alkaline.

Strong alkaline chemicals are especially corrosive to skin (it turns skin into soap). Alkaline chemicals neutralize acids but in the process can put out tremendous amounts of heat that can start fires and generate gases that can build up explosive pressures. Common alkaline chemicals are ammonia (a gas used in agriculture), cleaning ammonia (ammonium hydroxide), sodium hydroxide (Drano drain opener, Easy Off oven cleaner & Red Devil soap making Lye). These chemicals can be dangerous by themselves but are more dangerous mixed with acids.

COR means that the chemical is corrosive but not because of acid or alkaline properties. It might be corrosive because of it reacts violently with water and if exposed to the moisture in skin, damages skin. Chemicals used in the computer chip industry like phosphorus trichloride, boron trichloride, aluminum trichloride, and silicon tetrachloride are in this category.

Picture is a leak from a truck carrying 12 tons of phosphorous trichloride, which has the NFPA warning of Health=4 (deadly), flammability=0 (non-flammable), reactivity=2 (violent chemical change). The Specific Hazard is listed a Water Reactive. Corrosive and irritating to living tissue. Toxic level exposure to skin causes acid-like burns. In contact with water (in tissue or with liquid water) it creates hydrochloric acid and phosphoric acid.

You should feel at ease because in your chemistry kit, there are no chemicals that would warrant any of these warnings.

EASY OFF OVEN CLEANER: This is not in the kit but may be in your kitchen. One MSDS gives the rating of 3 for health, which is extreme danger (see diamond). It also states, "Inhalation: Not toxic by inhalation. Eye Contact: Corrosive to eyes. Skin Contact: Corrosive to skin. Signs and symptoms of overexposure include reddening of skin, tissue destruction, delayed pain. Ingestion: Not orally toxic; however, product is corrosive to mucosal membranes."

In this case, the MSDS is not exaggerating. One ingredient at 5% concentration is sodium hydroxide, which is quite corrosive, especially to the skin and eyes. The warning on the label on the can says to wear gloves, but it would also be a good idea to wear goggles as well.

A web site that has the MSDS for many household products is
http://householdproducts.nlm.nih.gov/
Be sure to visit it.

The chemical used as a soil substitute is called sodium polyacrylate:

As you can see from the NFPA sign the chemical is safe in all three areas: Health, flammability, and reactivity (explosiveness). One MSDS publisher does say it can be irritating to skin or eyes. (but that's about true of about any powder). This is a chemical in your kit.

FIRE SAFETY:  Getting burned or setting something on fire is a major concern. 

There are two labs that will need the use of a heat source.  You will use the stove or a microwave oven.  Whenever something gets heated, there is a danger of getting burned or starting a fire.    Also, glass sometimes breaks when heated.   So be extra careful on those two labs just like being careful when cooking.

GLASSWARE SAFETY: Glass is resistant to chemicals and heat, so it's a common item in labs. But as you know, when glass breaks, it can cut you.  Your kit has several items that are made of glass including a glass thermometer, which is probably the easiest item to break.  So be extra careful with the thermometer.  

Graduated cylinders are usually made of glass, but we choose plastic ones for the kit just for extra safety.  

CHEMICAL SAFETY:  Most chemicals in your kit are fairly safe to be around but that doesn't mean they are necessarily safe to touch, taste, or even smell.  For example, you have worked with gasoline, which is considered quite dangerous, but if you don't expose the gas to a flame, taste it, or inhale it, then you can handle it safely.  So working with chemicals in your kit is like that. They are fine if you avoid contact with them.

Gloves are included in the kit for the times your will be working with chemicals that are not good to contact.

EYE SAFETY:  Your eyes are the most vulnerable part of your body and the most important.   Your kit has goggles for eye protection.  The lab instructions will remind you when goggles are needed.

The goggles in your kit are made to resist liquid splashes to the eyes.  Normal glasses or other kinds of safety glasses are not good at stopping liquid from getting in the eyes.