Wow! Cave of Crystals!

Watch this incredible video of a cave in Mexico with 10m long crystals. Listen out for the narrator and how he describes some of them...a word we were learning about in science.

Shadows around school

Look at these shadows from school.
Can you tell what made them?
What shape are they?

Bigger box pinhole camera - better image with smaller hole and longer box

After school finished yesterday I looked at the partial eclipse using the cardboard roll pinhole camera

and using the cuboid box camera (see picture below)

...the images were small...how could I make the image larger?

Mr Parkin also took a picture using a digital camera with a coloured filter...but the image was unclear and too bright to see...see below

I thought for a few seconds and realised that if I made the box longer and kept the hole very small it would let the beams of light from the sun be further apart when they hit the screen...this would make the image bigger!

Below is a photo taken using the larger camera.  I enlarged it using photo software (picasa) but it looks a lot clearer.

You can see the grainy texture of the tracing paper, which I used as a screen.

This is the original photo of the screen before using picasa:

Did you manage to take any good pictures from your pinhole cameras?

Partial Solar Eclipse today - this afternoon - Bangkok

There is a partial solar eclipse due today.  This means that the moon will be travelling in between the sun (the big light source in the sky) and the earth (which is acting as a big "screen").

Safety: do not look directly at the sun.  See here for further safety information.
This is the best site I have found which shows when the eclipse is happening around the world and how much of an eclipse (how partial) it will be.



Here’s another link to solar eclipses on the BBC – looks like it is at 4:40???Conflicting information.



Here’s another animation.

We made some pinhole cameras.  Here is a copy of the instructions we used and some pictures of the cameras we made.  Unfortunately the images were not very clear, but the cameras WERE home made!

Light and Shadows

Here are some questions we are going to investigate today:

What do you need to make a shadow?
Punn: You need a light source and an object
How do you make a shadow bigger?
Seb:you move the object closer to the light source.
How do you make a shadow smaller?
How do you make a shadow change shape?
How do you make a shadow more blurry?

Can light travel around corners?
Samuel:No but if you use a mirror and a light source, you can make a reflection of the light move around a corner.
Can you make coloured shadows?

Where does light come from and what makes it change direction? Sources and reflection

Miss Kem and 3W scientists took some great photos today.

How many light sources can you see?

Which is the most reflective surface?

Can you recognise any of the places from our school?

Athena's illuminating light and shadow facts

Follow this link to see Athena's light and shadow facts.

There are some great safety tips here. This powerpoint was edited by Tushar.

I tried to show it in the same way as Tushar's and Luc's powerpoint, using scribd, but there was a technical problem. Oh well.

Unanswered science questions

Do you remember we came up with lots of "light and shadow" questions?

Can you answer any of them?

Send answers as comments, including where you found the answer(this is called a reference).
Who?
Who invented candles?
Who invented the light bulb?
What
What is light?
What are sunspots?
What is dark?
Where?
Where do shadows come from?
Where does light come from?
Where is the darkest place in the world/the universe?
When?
When was the light bulb/candle invented?
Why?
Why does light happen?
Why do we have shadows?
Why do we have rainbows?
Why are rainbows made of different colours?
Why don't the flames from the sun go out?
Why do shadows stretch?

Light and Shadows - the earth in space

Why does the sun appear to move across the sky?
Why does the sun create shadows which change in length and direction during the day? Look here for a great animation. What time on the animation is the shadow the longest? Send answers as comments - remember to put your name if you use the answer anonymously option.

Usually I show it in class by using a bright light, a globe and a piece of blutack shaped like a person!

This website shows the earth rotating and you can change the month of the year to show how much sun each part of the earth gets.

This website is a great animation of the earth rotating, while it orbits the earth and while the moon orbits the earth.

To see how to make shadows bigger or smaller using an object, a screen and a light source, look here.

Light and shadow vocabulary

Here are the words which we are going to investigate this lesson:
transparent, translucent, opaque, reflective, reflection, light source, block light, shadow, sun, light, bright, dull, mirror, rainbow, sunspot, convex, concave, lens, prism (not prison), eye, pupil, iris, sclera, cornea, retina, screen, colours

Lei's shadow data

Lei checked the length of a shadow each hour today. Here is her data:

 

9am: 39cm

10am: 10cm

11am: 5cm

12pm: 3cm

1pm: 34cm

2pm: 42cm

3pm: 54cm

 

Why was her shadow the shortest at 12pm?

What length do you think the shadow was at 8am?

Lei has a question: 

If you want the shadow to grow longer, do you have to make light source closer to or further away from the object?

Is there another way to make the shadow shorter?

Science - light and shadows

How can we find out answers to our questions? We thought of these ways:
Internet search and research
Reading books (non fiction) - e.g. encyclopedias, dictionaries,
TV(National Geographic, Discovery Science, Discovery) or DVD
Asking experts (scientists)
Radio
Test our ideas ourselves
Read a newspaper

We have a lot of questions!

If you find the answer, send it in!
Who?
Who invented candles?
Who invented the light bulb?
What?
What is light?
What are sunspots?
What is dark?
What makes the biggest shadow in the world/universe?
Where?
Where do shadows come from?
Where does light come from?
Where is the darkest place in the world/the universe?
When?
When was the light bulb/candle invented?
Why?
Why does light happen?
Why do we have shadows?
Why do we have rainbows?
Why are rainbows made of different colours?
Why can light be so bright and powerful?
Why don't the flames from the sun go out?
How?
How do you make electric light?
How can we measure light?
How is light made?
How hot (many degrees) is the sun?

Light and shadow

We started our topic on light and shadow today.

We went into the dark room (the guided reading book area) and took lots of shiny (reflective) things like mirrors, reflective gold paper, tinsel. We then turned off the lights (light sources). There were some lights that we could still see, like the computer screen, the LED lights on the A/C . We turned the computer off. We could not see the reflective materials because there was very little light to reflect.

We need a light source to see things.

We also talked about the pupil (a hole in your eye) and how light shines.

In the classroom we discovered that you can make a really short shadow but shining a torch (a light source) from directly above the pencil. This happens in our world at about midday when our biggest light source (the sun) is directly above us. In the late afternoon the sun is nearer the horizon and it casts a longer shadow.