Upper Grades Math & Science Support
M. Mackenzie - Harbor View Elementary - NMUSD - CA

Be a Viking, explore your universe with respect and an open mind.

ELECTRICITY AND MAGNETISM

You have learnt in 4 th grade that electricity and magnetism are related and that one can actually create a magnet with electricity (DC, direct current found in batteries.   At home your appliances work with AC, alternate current) and that magnets can produce electricity.   Let’s review some of the things you have learned in electricity.

Electric circuits :

In a DC electric circuit the constant flow of electric charge goes from high potential (- )to low potential (+).   In a DC circuit, electricity goes from the negative pole to the positive pole.

To builds an electric circuit you need a source of power ( a battery),   a conductor ( something that can carry electricity as opposed to an insulator which does nor), and something which will consume electricity such as a bulb or a motor.   It is very dangerous to attach a simple wire to the two ends of a power source; the battery could overheat.   This is called a short circuit because there is nothing to consume the electricity which flows in the loop.

There are 3 types of electric circuits you should know.

            Series circuits:   In this type circuit if any of the components is broken or removed, the whole circuit stops working because the flow of electricity is interrupted   (picture on the right below where bulb B is broken).   The elements are on a row, they are all placed on one single loop which connects all of the components.

Parallel Circuits : In this type of circuit if one of the bulbs break the other will still work because there is still an independent circuit. The elements are NOT all placed on one single loop connecting the components. Usually the bulbs are placed on circuits parallel to each other.

Mixed Circuit:   A mixed circuit has both parallel and series components.

Magnets ( objects that have a magnetic field) and magnetism ( property of objects to attract or repel other objects):   Remember that magnets attract objects that have iron, nickel, or cobalt in them.

All magnets have 2 poles, a North and a South pole.   Earth being itself a giant magnet has a North magnetic pole and a South magnetic pole.   These poles are not located where the North and South geographic Poles are.

The needle of a compass, which can be made by rubbing a small iron bar against a magnet or by using magnetite, will try to align itself with the North - South magnetic field on earth.   This field is the strongest at the two poles. Remember how we hung all those magnets in class and they all aligned with my boat compass?

	Opposite poles attract each other and there is a strong magnetic field.
	Same poles repel each other ; there is a weak magnetic field where the 2 poles are close to each other

Electric circuits produce magnetic fields and vice-versa.   Students have seen that if one places a compass over the wires of an electric circuit the needle of the compass will deviate.   Students also built electromagnets by wrapping copper wire around a nail.   When the wire was attached to a power source the nail became magnetized and could ‘pick up’ a certain number of washers.   The number washer attracted was directly related to the number of coils on the nail.   The more the coils, the stronger the magnet.

Just like magnets, you have noticed that electrically charged objects act like magnets.   Objects with same charge repel each other (the 2 balloons rubbed both with the silk scarf or on your hair) or the 2 balloons of which only one was rubbed and could then attract the other.   We did this to give an example of static electricity. I am very proud that some of my 4th graders and their parents did the experiment of the balloon and the water hose at home ( we saw it in the film)and they did notice that the water was slightly deflected. I love it when students get their parents involved.|

Electromagnets produce a magnetic field and act like magnets. The big difference is that hey can be turned off and on and are used in devices such as door bells, electric motors, and earphones.

We used this property of electromagnets to build a simple doorbell; A simple metal bar which was attracted by an electromagnet and which would hit a bell when the circuit was opened.

Electrical energy can be converted to light (bulb), heat (toaster), and kinetic (movement) energy by the use of electromagnets or electric motors.

Kinetic energy can be converted to electrical energy by the use of generators and alternators which use magnets.

Light also can be converted to electrical energy directly (solar panels).

An ecosystem is an area where living (biotic) and nonliving ( abiotic) things interact.

            LIVING (biotic)                                                          NON-LIVING (abiotic)
            Plants                                                                          water
            Animals                                                                       sunlight
            Bacteria                                                                      soil
                                                                                                air

Roles in an ecosystem:

Consumers:   cannot make their own food, so they consume plants and animals.
            1) herbivore – eats plants.
            2) carnivore – eats other animals (meat).
            3) omnivore – eats both animals and plants.

Decomposer
            ( FBI ) recycle dead plants and animals back into the ecosystem.
                        F   fungus
                        B   bacteria
                        I     invertebrates (worms, insects)

Producers:   are plants, which are capable of producing their own food via photosynthesis.

Photosynthesis: Plants use light, water, and carbon dioxide in the air to produce sugars. During this process they emit oxygen.
Here is the formula for photosynthesis. 6 CO₂ + 12 H₂O + light → C₆H₁₂O₆ + 6 O₂

Translation for this chemical reaction: You start with 6 molecules of carbon dioxide and 12 molecules of water and you add energy provided by light (sun energy) and you get one molecule of sugar, 6 of water and 6 of oxygen. Remember that nothing is destroyed but are rearranged. A chemical formula is like what we saw in algebra; you must be able to find on the other side of the equation whatever you had when you started.

Plants depend on animals for pollination (flowers and bees) and for seed dispersal.          There are 4 methods for seed dispersal.

                        1.) Wind – dandelion, maple seeds (look like helicopters).
                        2.)   Water – coconut.
                        3.) Attaching themselves to animals.
                        4.) Eaten by animals …….    And then recycled somewhere else.

Earth Sciences

Rocks are made of minerals.  

Properties of minerals:
            - color
            - luster (metallic, shining like metal or non-metallic (dull)
            - streak ( color left when rubbed on a tile)
            - hardness ( Mohs Hardness Scale; 1 = soft (talk) and 10 = hard (diamonds)

There are 3 types of rocks depending on how they were formed.

1.)   Igneous – made form lava or magma that has cooled on or near the earth’s surface.
            Cooled slowly – large crystals.   Cooled rapidly – small crystals

2.)   Sedimentary – made when sediments ( mud, sand, slit from weathering) get cemented together.   Most fossils are found in sedimentary rocks.

3.)   Metamorphic – (remember butterfly metamorphosis) made when rocks have been changed by heat and/or pressure.

Rocks can be broken down ( weathering and erosion) by water, wind, waves, chemicals, earthquakes or ice for example.

Moving water is the most powerful cause of eroding rocks (rounded shape) / landforms, however landslides, volcanic eruptions, and earthquakes can rapidly change Earth’s surface too.