Blind Spot - Revision history

imported>Stwikiadmin at 20:10, 5 April 2016

2016-04-05T20:10:17Z

← Older revision		Revision as of 20:10, 5 April 2016
Line 1:		Line 1:
	== ~~Age ==~~		{\| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
			\| [[Biology]]:
			\| The Eye, Blind Spots
			\|-
			\| Grade Range:
			\| [[Elementary School]], [[Middle School]]
			\|-
			\| Format:
			\| [[Hands-on]]
			\|}

	~~Middle School~~		This is a good demonstration for a science night, or when you have groups rotating through tables. It is easy for the students to do, and the concept is one that they can easily try at home to show their family and friends!

	~~== Format ==~~

	~~Hands-on~~

	== Materials ==		== Materials ==

	~~Jelly Beans~~		* Dot and Cross papers
	~~Cup for Jelly Beans~~		* Cardboard Tubes
	~~Papers with 2 spots in appropriate locations (for blind spot demo)~~
	~~Paper towel tubes (they are decorated with lots of colored tape)~~
	~~Senses poster~~

	== Safety Precautions ==		== Safety Precautions ==

	~~Science Theatre demonstrators must keep~~ the ~~safety~~ of ~~themselves and their audience in mind at all times. All Science Theatre demonstrators must have read through~~ the Safety ~~Training~~ page. The ST Safety Box with first aid kit, fire extinguisher, etc. should always be available to demonstrators. Always wear safety gloves, glasses, and a labcoat if handling chemicals; always perform potentially dangerous demonstrations at a safe distance from the audience; and always keep a very close eye on any volunteers you call from the audience. Don’t let anyone choke on the jelly beans.		Please read the General Safety section of the [[Demonstration Safety]] page before performing this demonstration.

	~~== Preparation ==~~

	~~Put the jelly beans in the cups. Photo copies of the blind spot card should be made for each participant. Also it is useful to have a large version of the eye anatomy to use when presenting this demo.~~

	== Demonstration ==		== Demonstration ==

	~~Participants are given~~ a ~~card~~ with ~~an X~~ and ~~a Dot on it~~. ~~To find their blind spot they are instructed to:~~		# Give each student a cardboard tube and a sheet with a dot and cross. Have them place the paper down on a table or surface in front of them, with the dot on their left side and cross on their right side.
			# Explain that they will be finding their blind spots, and give them the following instructions:
	~~• Hold~~ the ~~card~~ in ~~their right hand~~ with the X on ~~the~~ left side ~~about a foot away from~~ their ~~face~~		## Close their right eye, or cover it with their right hand. Hold the tube up to their left eye.
			## While looking at the dot, slowly move closer to the table. At some point, the cross will disappear while they are looking at the dot!
	• Close their ~~left~~ eye (or cover with ~~left~~ hand~~) and look at~~ the ~~X with~~ their ~~right~~ eye ~~or vice versa~~		## When they see the cross disappear, they can then try it with their right eye. Make sure they flip the paper around when they try it!

	~~• Slowly~~ move the ~~card in until the Dot disappears~~. ~~You’ve found your blind spot!~~

	At ~~this~~ point the ~~image of the Dot is falling on the blind spot. You~~ will ~~find that the location of the card left to right is less important than the distance the card is from the eye. Participants should be reminded to stare~~ at the X the ~~entire time. It is natural for the eye to shift to the dot when it begins to~~ disappear, ~~however~~ they ~~must stare at the X in order to not see the dot. This may prove difficult for younger children. This test~~ can ~~be repeated~~ with ~~the~~ right eye ~~closed by turning the card so that the X is on the right~~. ~~The eye anatomy figure describes~~ the ~~location of the blind spot, and explains why this part of the retina lacks light receptors.~~

	== ~~What to Say~~ ==		== Why This Works ==

	~~Did you know~~ that ~~there~~ is a ~~certain spot where your eyes cannot see things? Well~~ to ~~find where it~~ is~~, everyone needs~~ to ~~take~~ one of ~~these papers~~. ~~Hold it out in front~~ of ~~you~~ and ~~cover one eye~~.		In the back of the eye is an organ called the retina, which contains a layer of very specialized cells that can sense visible light. When light strike one of these cells, the light is absorbed. Then, a signal is passed to the vision center of the brain by way of nerve cells, and the signal is translated as an image. The nerve cells which connect the retina to the brain are collected together at one spot in the back of the eye, and they form the optic nerve. This spot has no sensory cells of its own, however, and thus light which falls on it is not detected. This is the location of the blind spot!

	~~== Why It Is ==~~		Normally, we don’t notice we have a blind spot for several reasons. First, the blind spot is always in our peripheral vision. That means that it is in a spot in our vision that we are not focusing on, so it is never going to interfere with what we are looking at directly. Secondly, our eyes are constantly on the move. We are always looking at new things and changing focus, so nothing remains in the blind spot for very long, which makes it hard to notice. Lastly, our eyes compensate for each other. Our eyes work together to create a full image, so what falls on the blind spot in one eye will be visible to the other. All of these factors come into play for this demonstration: by covering one eye, we force the other eye to work alone. By staring at the dot, we limit how much the eye is moving. And since we are paying attention to our peripheral vision, we notice our blind spot!

	~~In the back of the eye is an organ called the retina~~, ~~which contains a layer fo very specialized cells which can sense visible light. When light particles (photons) strike one of these cells~~, ~~the light is absorbed. Then~~ a ~~signal is passed to the vision center of the brain by way of nerved cell,~~ and the signal is perceived as an image. The nerve cells which connect the retina to the brain are collected together at one spot in the back of the eye to form the optic nerve. This spot has no sensory cells, and thus light which falls on it is not detected. This is the location of the blind spot. ~~Normally, we don’t notice we~~ have ~~a blind spot for several reasons. First~~, the ~~blind spot is always in our peripheral vision~~, ~~never is~~ it going to interfere with what we are looking at directly. Also our eyes are constantly on the move, therefore nothing remains in the blind spot for very long. Lastly, our eyes compensate for each other in that what falls on the blind spot in one eye will be visible to the other. All of these factors come into play for this demonstration: you cover one eye, stare at the X (keeps your eye from moving), and the dot disappears from your peripheral vision.		''Note: Sometimes a student, especially younger ones, will have a hard time with this demo and can’t find their blind spot. Either have them try it again, move the paper slower, or just don’t make them do it.''

	• Sometimes kids, especially younger ones, have a hard time with this demo and can’t find it – either have them try it again, move the paper slower, or just don’t make them do it…*		== Additional Information ==

	~~== Real Life Examples ==~~		* This pairs well with the [[Temporal Tops]].

imported>Stwikiadmin: Created page with "== Age == Middle School == Format == Hands-on == Materials == Jelly Beans Cup for Jelly Beans Papers with 2 spots in appropriate locations (for blind spot demo) ..."

2013-09-11T23:26:51Z

Created page with "== Age == Middle School == Format == Hands-on == Materials == Jelly Beans Cup for Jelly Beans Papers with 2 spots in appropriate locations (for blind spot demo) ..."

← Older revision		Revision as of 23:26, 11 September 2013
(No difference)

imported>Stwikiadmin: Created page with "== Age == Middle School == Format == Hands-on == Materials == Jelly Beans Cup for Jelly Beans Papers with 2 spots in appropriate locations (for blind spot demo) ..."

2013-09-11T23:26:51Z

Created page with "== Age == Middle School == Format == Hands-on == Materials == Jelly Beans Cup for Jelly Beans Papers with 2 spots in appropriate locations (for blind spot demo) ..."

New page

== Age ==

Middle School

== Format ==

Hands-on

== Materials ==

Jelly Beans
Cup for Jelly Beans
Papers with 2 spots in appropriate locations (for blind spot demo)
Paper towel tubes (they are decorated with lots of colored tape)
Senses poster

== Safety Precautions ==

Science Theatre demonstrators must keep the safety of themselves and their audience in mind at all times. All Science Theatre demonstrators must have read through the Safety Training page. The ST Safety Box with first aid kit, fire extinguisher, etc. should always be available to demonstrators. Always wear safety gloves, glasses, and a labcoat if handling chemicals; always perform potentially dangerous demonstrations at a safe distance from the audience; and always keep a very close eye on any volunteers you call from the audience. Don’t let anyone choke on the jelly beans.

== Preparation ==

Put the jelly beans in the cups. Photo copies of the blind spot card should be made for each participant. Also it is useful to have a large version of the eye anatomy to use when presenting this demo.

== Demonstration ==

Participants are given a card with an X and a Dot on it. To find their blind spot they are instructed to:

• Hold the card in their right hand with the X on the left side about a foot away from their face

• Close their left eye (or cover with left hand) and look at the X with their right eye or vice versa

• Slowly move the card in until the Dot disappears. You’ve found your blind spot!

At this point the image of the Dot is falling on the blind spot. You will find that the location of the card left to right is less important than the distance the card is from the eye. Participants should be reminded to stare at the X the entire time. It is natural for the eye to shift to the dot when it begins to disappear, however they must stare at the X in order to not see the dot. This may prove difficult for younger children. This test can be repeated with the right eye closed by turning the card so that the X is on the right. The eye anatomy figure describes the location of the blind spot, and explains why this part of the retina lacks light receptors.

== What to Say ==

Did you know that there is a certain spot where your eyes cannot see things? Well to find where it is, everyone needs to take one of these papers. Hold it out in front of you and cover one eye.

== Why It Is ==

In the back of the eye is an organ called the retina, which contains a layer fo very specialized cells which can sense visible light. When light particles (photons) strike one of these cells, the light is absorbed. Then a signal is passed to the vision center of the brain by way of nerved cell, and the signal is perceived as an image. The nerve cells which connect the retina to the brain are collected together at one spot in the back of the eye to form the optic nerve. This spot has no sensory cells, and thus light which falls on it is not detected. This is the location of the blind spot. Normally, we don’t notice we have a blind spot for several reasons. First, the blind spot is always in our peripheral vision, never is it going to interfere with what we are looking at directly. Also our eyes are constantly on the move, therefore nothing remains in the blind spot for very long. Lastly, our eyes compensate for each other in that what falls on the blind spot in one eye will be visible to the other. All of these factors come into play for this demonstration: you cover one eye, stare at the X (keeps your eye from moving), and the dot disappears from your peripheral vision.

• Sometimes kids, especially younger ones, have a hard time with this demo and can’t find it – either have them try it again, move the paper slower, or just don’t make them do it…*

== Real Life Examples ==