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Adoptive mother Home Educator Author of Living with Infertility - a Christian Perspective www.frogotter.net

Electronics Course – Briefcase Alarm

Briefcase Alarm

Arrival Craft – Match the Component to the Name / Symbol, Resistor Code colour by number

CircuitSymbolMatching

Colour by Number – Google Docs

Introduction – Last week, we made circuits to turn LEDs on and off.

Show a model, to remind everyone.

Another way of thinking of electrical current is like something flowing through a hose.

Show a length of clear pipe with a knotted string in it.

We can pull the string through the pipe and it goes round and round just like an electrical charge.

But what happens if I cut the wire?

Cut through the pipe and string.

There’s no circle of string anymore and I can’t keep pulling it through.

In our first week we made Steady Hand Games.

Show a Steady Hand Game to remind the children, if there’s time, see if anyone wants a turn.

The whole of the game is really one big switch, since a switch is just a way of opening and closing a circuit.

In your Electronics Kit today you have push switches. We’re going to add them to our LED circuits.

Use giant model to show how to add push switches to circuits.

I made the giant model using card and velcro, so we could move giant components around a giant breadboard. The children found it really helpful.

Individual Task: Add a push switch to the LED circuit.

 
Regroup: These switches are boxed in so it can be hard to see how they work. I’d like you all to have a go with foil and card and see if you can make a push switch of your own and use it to turn your LED on and off.

Individual Task – Make a simple push switch out of card and foil.

PushSwitch


Break for drink and snack

 

Regroup: Sometimes we want our circuits to be a bit cleverer. Rather than needing a person to switch them on and off by hand, we want them to respond to their surroundings.

Street lamps, for example, switch on when it’s dark and off when it’s light.

Does anyone know how they do that?

Street lamps are fitted with LDRs – light dependant resistors – which respond to the amount of light around them.

We’re going to replace the switches in our circuits with LDRs.

 

Individual Task: Make circuits so that LEDs come on when there is light.

LDR

Regroup: With our circuits, the LEDs came on when it was light and went off when it was dark – the opposite way round to how we would want a street light to work.

But, LDRs have a high resistance in the dark and a low resistance in the light, so we need another component to get this function.

We can use a transistor.

Has anyone heard of transistors before?

Transistors have three legs. They are able to function as a clever switch. If a small current flows across the base and emitter, the transistor allows a larger current to flow across the collector and the emitter. This means we can use the transistor as a switch that is turned on by a small current of electricity.

For example, we can use the transistor as a clever switch that will turn on the light when the LDR is in the dark.

Demonstrate on the big model, then show on the little breadboard.



That’s what we’ll be doing together next week.

Electronics Course – LEDs and Resistors

LEDs and Resistors

Arrival Craft – Horra Island Sheets from Horrible Science Book.

Introduction – Did anyone get a chance to look for switches over the past week? Did you find any?

Fantastic. We’re going to have a go at making push switches today. But, we’re going to be using LEDs in our circuits, so before we start working with those, we need to talk about resistors. Does anyone know what resistance means?

Some things are conductors of electricity and some things aren’t, as you already know.

But, it’s not a binary system. There are levels of conductivity. When things conduct electricity, but not very well, we say that they have a lot of resistance.

We’re going to be looking at resistors today.

We can use multimeters to measure how much resistance things have.

 
Individual Task – Test various materials for resistance, use multimeters.

TestingResistance

Regroup: Resistors are important to regulate the flow of electricity.

They work like funnels, allowing only a certain flow through.

Use funnels to show how resistors control the flow of electricity – bigger and smaller funnels could demonstrate tolerance of resistors?

We’re going to be making some more circuits today, but we’re going to be using LEDs. Has anyone used them before?

Light Emitting Diodes don’t like having too much current going through them, so we use resistors to control the flow of electricity.

 

Individual Task – Make a simple circuit with an LED and a resistor in it.

LEDcircuit

Then have a go at making your own push switch with card and foil.

PushSwitch

Break for drink and snack.

 

Gather Together: Hopefully everyone has managed to get one LED to light.

Did anyone manage to read the current of their circuits? Did you notice anything about the currents from different parts of the circuit?

Whichever part of the circuit you read the current from, the current was exactly the same.

It can help to think of electricity as a loop all the way around your circuit.

Did anyone notice what happened when you put the resistor after your LED instead of before it?

It worked just as well, it may seem strange at first, but it doesn’t actually matter which way round the LED and the resistor are, either way the resistor regulates the flow of electricity.

I’ve got a new challenge for you now, I would like you to have a go at connecting two LEDs in your circuit.

 

Individual Task: Connect two LEDs in series and then in parallel.

TwoLEDs

Finish up: When you connected the two LEDs in series, what happened?

They didn’t light up because there isn’t enough current for two LEDs.

Did anyone manage to get both LEDs to light up?

How did you do it?

You can get two LEDs to light, if you connect them in parallel rather than in series. You split the current into two separate loops.

Did anyone manage to read the current of a circuit with two LEDs in it?

The current increases when you have two LEDs.

Next week we’re going to look at sensors. These are special components that allow appliances to respond to their environment. See if you can find any around your house.

Electronics Course – Switches

Switches

Arrival Craft – Aluminium atom models 

AluminiumModel

Grid colouring sheets.

Introduction: What is electricity? Electricity is a flow of electrical charge, caused by the movement of electrons.

As you saw in your models, atoms are made up of nuclei and electrons. In metals, the electrons on the outermost shell are not very strongly attracted to their nuclei. This means that the electrons can move freely.

We’re going to make a model now to show how the ‘sea of electrons’ allows an electrical charge to flow in a metal.

 

Individual Task: each child should take a plate and stick half a dozen marshmallow halves to it. They can then sprinkle a handful of Millions sweets onto the plate. When they tip the plate, the Millions will flow, around the marshmallow halves from one end of the plate to the other.

ReGroup: Hopefully that gives you a bit of a picture of how electrons flow in a circuit.

We’re going to make another model altogether now.

Give the children a string long enough to pass all the way around the room, with ten or so beads strung on it.

If we pass this bead along the string, we can see how an electrical charge moves along a wire.

We can think of the electrons as beads moving along a string, If they keep moving round and round, the charge keeps flowing round the circuit and it can drive components that we put in the circuit.

What would happen if I cut the string?

If the string is cut, the beads cannot flow anymore.

In order for your circuits to work, they must be complete. Any break in the circuit will stop it working completely.

We’re going to make our very first simple circuits now. I have a small electronics kit for each of you, I’ll be adding new pieces to it as we progress through the course, but we’re going to start with just a few pieces.

Today we’re going to look at buzzers.

Does anyone know how buzzers make a noise?

Buzzers make a noise by vibrating. We’re going to be using piezo buzzers. These have a piezoceramic disc inside them which vibrates when an electric current passes through it.

 

Individual Task: Find the components in the kit and find out their names.

Make a circuit that switches on a buzzer when you touch two wires together.

Break for drink and snack.

 

ReGroup: You’ve made a simple circuit that buzzes when two wires touch. This is the basis for an electronic game.

Show a steady hand game you’ve already made.

I’ve looped one of my wires around the other. When the two wires touch, the buzzer sounds. But, if I can move one wire past the other, without letting them touch, then the buzzer won’t sound.

Would anyone like to have a go with my steady hand game?

Let a child try, briefly.

Individual Task: Make your own steady hand game.

SteadyHandGame

Science Club – Nervous System

Week Six – Nervous System

Arrival Craft: Paper brain model from Scholastic model book.

 

Introduction: Our brains are the control systems of our bodies. They collect information from all over our bodies and send messages back.

We use special cells to carry these messages around, does anyone know what these cells are called?

They are neuron cells.

The central part of the neuron – a long thin body – is called the axon, and it is covered with myelin sheath, which is a fatty tissue that works as an electrical insulator.

Neurons have two ends: a receiving end with dendrites and a transmitting end called the axon terminal.

There is a cell body with a nucleus in the middle of the dendrites.

Individual task: Make neurons out of pipecleaners PipecleanerNeurons

Gather Together: Does anyone know how our nerves get information back to our brains for processing?

Nerves send messages using electrical signals, these travel up the spinal cord to the brain stem.

Does anyone know where our spinal cord is?

Show on the anatomy model.

Individual task: Give out polystyrene people, so the children can put brains and spinal cords onto their models. Brains

Break for drink and snack – Try to ice brains and spinal cords onto gingerbread cookies!

Regroup: Does anyone know the names of any of the parts of the brain? Look at the brain model together.  Name the parts as you take them out, then ask the children to try and put them back in place.

I haven’t got human brains for us to dissect, I have sheep brains instead. Can anyone guess which part of the brain is much smaller on a sheep? The Cerebellum which is used for learning and co-ordination. Can anyone guess which part of the brain is larger on a sheep? The olfactory bulb, which is used for processing scents.

Individual task: Dissect brains. Children can look at pictures and try to identify regions of the brain.

Science club – Circulatory System

Week Five – Circulatory System

Arrival Craft: Paper heart from Scholastic model book.

Introduction: Today we’re looking at the circulatory system. Does anyone know what the circulatory system does?

The circulatory system moves blood around our bodies. What organ pumps all the blood around our bodies?

The heart is a big muscle that pumps blood around our bodies.

Does anyone know where their heart is?

If children are unsure, ask a volunteer to find the heart on the anatomy model.

Individual task: Children can make hearts out of plasticine and put them on paper people. body 

Gather Together: We’re going to do something a little bit different today. I have several activities that we can only really do one or two at a time. So, I’m going to put a different activity on each table. When you finish with the activity on your table move around to the next table. Everyone will get a chance to do everything and, when we’ve all visited all the tables, we’ll have snack time.

Set up microscope on one table so children can look at blood cells.

Set up heart models on another table so children can look at the hearts, take them apart and put them back together.

Set up blood pressure monitor and stethoscope on another table so children can have a go at taking their blood pressure and listening to one another’s hearts. bloodpressure

Set up CPR dummy on another table so that children can practice CPR. (These can be pretty pricey, but they make inflatable ones now, which the kids love see details here.)

Break for drink and snack.

Gather Together: What is our blood for?

There are four main components of blood and they each have their own job: red cells transport oxygen, white cells fight viruses, platelets build scabs, plasma transports nutrients and hormones.

 

Individual task: Make models of blood, using sweets to represent the different types of blood cells. bloodcells

Science club – Respiratory System

Week Four – Respiratory System

As children arrive, ask them to measure their lung capacity and their height, then plot both of these on a graph.

Arrival Craft: Paper respiratory system from Scholastic model book.

 

Introduction: As you arrived, I hope that you were able to test your ‘peak flow’ and measure your height.

I wanted to test to see if there was a correlation between height and peak flow.

Let’s look at our results (talk about strong and weak correlation).

We’re going to make two model lungs together. We’re going to put one into each of these bowls.

The first one is very easy to make and I’m going to make it all by myself, I’m going to blow up this big balloon.

The second one is a bit fiddly, so, I’m going to need your help. I need you to each inflate a small balloon – try to make it as round as you can, then work out the volume and the surface area of your balloon and write it on the big board. lungs

A=4πrsquared; V=4/3πrcubed; C=2πr

(for surface area, divide by six, square it, times by 12; for volume, divide by six, cube, times by four).

Finally, I’m going to give you a puzzle to think about, how can we blow out hot air when we want to warm our hands and cold air when we want to cool soup?

Individual Task: Blowing hot and cold experiment. blowingexpt

Break for drink and snack

Gather Together: While you were having your snack, I worked out the total volume and surface area of our two lung models.

Which model has the biggest surface area? Which one has the biggest volume?

Which one looks most like the structure of our real lungs?

Let’s have another look at the body apron. Would someone like to come and wear it so we can see where our lungs are?

Once a child is wearing the apron, ask them to identify the lungs and the trachea.

Final Activity: We have looked at blowing hot and cold air, but I would like to finish with one last experiment. If you take a straw and blow through it onto your hand, will it feel hot or cold?

Give out straws. Ask children to hold the straw just a few millimetres from their hand then blow through it.

Does it feel hot or cold?

I found that if I hold the straw very close to my hand and blow hard, it feels hot directly under the straw, but cold all around the edges.

Science club – Urinary system

Week Three – Urinary System

Arrival craft: Paper urinary system from Scholastic model book.

Introduction: Last week we looked at the digestive system. Closely connected to that is the urinary system. Does anyone know what it does?

Our urinary system gets rid of extra water and various wastes that our bodies don’t need.

Our kidneys play a very important role in the urinary system. They filter waste out of our blood.

Do you know how filtration works?

Filtration is a way of separating mixtures.

Show the mixtures we made earlier (lego and sand, sand and rice, rice and pasta, sand and water), ask the children how they would separate them and get a volunteer to try: there are colanders, sieves and filter paper to use.

When we look at real kidneys, do you think they will have big holes like the colander in them?

Why not?

The substances – like salts – which kidneys filter out of blood are much smaller than pasta, rice, or even sand. So the holes need to be small too.

Individual task: Make paper kidneys.

Break for drink and snack.

Gather Together: Does anyone know whereabouts on the body our kidneys are?

If nobody knows, encourage the children to look at the paper anatomy models we’re building.

I have an anatomy model that we can look at, can we name the digestive organs, and find the kidneys.

Ask volunteers to come up, name the digestive organs and remove them from the model, until we find the kidneys.

Before you cut into your kidney, try to find the tubes coming out of it. There should be three, what do you think they are for?

The renal artery (thicker than vein) carries blood to the kidneys; the renal vein carries blood back to the heart;  the ureter carries urine to the bladder.

Kidneys are a distinctive shape, they look like kidney beans.

They have a very distinctive shape inside too, the middle is made of triangle shaped tissues – these are called ‘renal pyramids’.

After you cut your kidney in half.

Demonstrate with one of the kidneys.

You can try to find the renal pyramids.

How many pyramids does your kidney have? Can you see the stripes on your pyramids? Are they vertical – going towards the centre of the kidney – or horizontal? You could add these features to your paper kidneys,

Individual task: Dissect Kidneys. kidneydissection