For example, if you ask a child what causes something to sink, they will usually say an object sinks because it is heavy. In order to understand density, students need a lot of practice with measuring density and examining the properties of objects in relationship to density. Download the Buoyancy and Density: Middle School Unit Plan document pdf for a series of activities to help students understand density and buoyancy.
The basic sinking and floating activities can be carried out with very young children. The mathematical calculations for density can be introduced between fourth and eighth grade. Students need to apply the concept of density over and over again in order to understand the difference between weight and density.
Just calculating the mathematical formula for density does not help students understand density. Having them measure the densities of real objects will help them understand the meaning behind the mathematics. Check Your Thinking: What do you need to measure in order to determine the density of snow? The attached two activities — the Snow Volume, Temperature and Density pdf and The Science of Snow pdf — engage students in collecting data to calculate the density of snow.
They will also gather data on the temperature of the snow. Use the Snow Field Data Sheet pdf to record data while outdoors. The data sheet can be used to gather data on snow along a meter transect, with a stake placed every 5 or every 10 meters. Or you can gather data at several different locations record descriptions of each location. View the photos below that show examples of students and teachers collecting snow samples. Figure 5. Image from Dr. Delena Norris-Tull. By trapping heat energy, snow restricts the depth of the frost layer, or area of soil containing ice.
A significant accumulation of freezing rain lasting several hours or more is called an ice storm. Most precipitation that forms in wintertime clouds starts out as snow because the top layer of the storm is usually cold enough to create snowflakes. How warm can an igloo get? Temperatures outside can sometimes reach up to minus 45 degrees chilly!
A: A snowflake begins to form when an extremely cold water droplet freezes onto a pollen or dust particle in the sky.
This creates an ice crystal. As the ice crystal falls to the ground, water vapor freezes onto the primary crystal, building new crystals — the six arms of the snowflake. Freezing rain develops as falling snow encounters a layer of warm air deep enough for the snow to completely melt and become rain. It also means that your home is receiving an extra layer of insulation against cold outside temperatures. Well actually, pure water is an excellent insulator and does not conduct electricity.
The spaces in the crystal are larger than the spaces between molecules in the liquid. It is generally safe to eat snow or use it for drinking or for making ice cream, but there are some important exceptions.
If the snow is lily-white, you can safely ingest it. Believe it or not that snow can actually be used to keep you warmer when the bitter cold strikes. That air is constricted, which then slows the process of heat transfer from the cold air outside through the snow layer.
This is why some animals in colder climates build snow caves to borrow into for hibernation during winter. Another good example of using snow for insulation would be taking snowfall in your backyard, and piling it up against the outer walls of your house.
This layer of snow would act as a second layer of insulation to keep the extreme cold out.
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