X Marks the Blind Spot

Transcription

1 X Marks the Blind Spot Human Body 10 minutes In this activity, students will learn about how their eyes and brains work together to trick them. Materials Needed 3x5 index cards Black marker Ruler or straight edge for drawing a line Steps: 1. Draw a bold black dot near the middle of one end of a blank index card. 2. Draw a bold black X near the middle of the other end. 3. With the X on the right side of the card, hold the card in front of you at arm s length. 4. Close your right eye and look straight at the X with just your left eye. Can you also see the dot? When you look one way and see something in another direction, you are using your peripheral vision. 5. Focus on the X, but notice what the dot does as you bring the card close to you. The dot will disappear, but as you keep moving closer it will show up again. Experiment a little to narrow down the exact spot where the dot disappears. 6. Try it again, but this time close your left eye and focus on the dot with your right. Does the same thing happen with the X? 7. Turn the card 90 degrees, and try it again. What happens? Turn it another 45 degrees and see what happens. 8. Now draw a straight line from one edge of the card to the other through the dot and the X. Turn to card horizontally like the first time you tried this, close one eye, and try it again. Notice that even though the dot or the X disappeared, the line kept going right through that spot.

2 Explanation: Did you know that there is a part of your eye that can t see? Light travels through the opening in your eye ( pupil) to the retina, which is like a projection screen in the back of your eye. It is full of light receptors that let you see. There is one spot on your retina that doesn t have any of those cells. That spot is where your optic nerve passes through. So, when that is lined up just right, you can t see the dot or you can t see the X. When the line you drew passed through your blind spot, your brain automatically filled in the missing information to make it continuous. That s why you don t notice your blind spot in your day to day life Your brain just fills it in based on the image it sees around it. Fun Fact: An octopus has no blind spot! Their eyes are constructed in a way that makes their optic nerve never interrupt their retina.

3 Blood Human Body 5 15 minutes In this activity, students will explore what makes up our blood in a real hands on way! Materials Needed Ingredients for one tub of blood: (Make as many as you want) Large plastic container Red water beads, hydrated in advance per the package instructions (note they can be hydrated in the large plastic container) Ping pong balls Red craft foam Steps: 1. Cut the red craft foam into small rectangles. These will be your platelets. 2. Put the red water beads into the plastic container, if they aren t already there. Add the craft foam platelets, some ping pong balls, and some water. 3. Explore the blood you have created! Have students feel, squish, and play with all the different parts in the blood and try to guess what they are. 4. Explain that the red water beads represent the red blood cells that carry oxygen through your body. 5. Explain that the ping pong balls represent the white blood cells that fight bacteria, viruses, and other germs or contaminants. 6. Explain that the red craft foam pieces represent the platelets that help heal cuts. 7. Explain that the water represents the plasma that helps the blood move through the body.

4 Fun Fact: All blood isn t red. Crabs have blue blood. Earthworms and leeches have green blood. Many invertebrates, such as starfish, have clear or yellowish blood. The human body manufactures 17 million red blood cells per second.

5 How Does a Lung Work? Human Body minutes In this activity, students will build a model of a lung to learn about how the lungs and diaphragm work together. Materials Needed Per student: 1 plastic drink bottle (may want to be pre cut depending on age) 1 straw 1 elastic band 2 balloons 1 glob of playdough A few per group: Scissors Steps: 1. Carefully remove the bottom of the bottle by poking a hole with the scissors and then cutting around the bottle. 2. Tie a knot in the open end of one balloon, then snip off the large sealed end. 3. Place the freshly cut balloon opening around the bottom of the drink bottle. 4. Put a straw into the opening of the other balloon, using a rubber band to hold it in place. Be sure that the straw is not crushed. You should be able to blow air through the straw and into the balloon. 5. Insert the straw and balloon into the neck of the drink bottle, leaving only part of the straw sticking out the top. Again, be careful not to crush the straw. 6. Use playdough to mount the straw in the bottle opening, sealing the area around the straw completely. 7. Hold the bottle and gently pull on the balloon knot that is connected to the bottom of the bottle. Watch what happens to the balloon inside the bottle. Let go of the knot and watch what happens.

6 Explanation: When you pull down on the knotted balloon, it makes the inside of the bottle bigger. Something has to fill in that extra space so air comes rushing in through the straw. The air coming in fills up the balloon and it expands. When you let go of the knot, the air goes out and the balloon deflates. That is just like how our lungs work. When we breathe in (the straw) our lungs fill (the hanging balloon) and our diaphragm moves down (the knotted balloon) to make room. Real World: Every day our lungs breathe in 11,000 liters of air! That is equal to 3000 milk jugs or about 20,000 of the bottles you just used!

7 Pumping Heart Human Body minutes In this activity, students will build a heart chamber to see how the heart pumps blood through the valves and to the body. Materials Needed Per group of 1 4 students: 1 mason jar 1 large balloon 2 flexible drinking straws Water to fill half of the jar About 1 foot of tape Pan, sink, or tub A few: Scissors Poking objects (wooden skewer, sharp pencil, etc.) Extra balloons Steps: 1. Fill the jar halfway full with water. 2. Cut the neck of the balloon off at the point where it begins to widen. Set the neck aside (a). 3. Stretch the rest of the balloon over the mouth of the jar (b). Pull the balloon as tight as possible. It should lie flat along the top of the jar. 4. Carefully poke two holes in the middle of the balloon, about an inch apart, using the poking object. 5. Put the long end of a flexible straw into each of the holes. The rubber top should seal against the straws. If it doesn t seal securely, start over with a new balloon.

8 6. Slide the balloon neck from Step 2 onto one of the straws, with the cut end up to make a flap. 7. Secure with tape. 8. Set the jar into the pan, sink, or tub. 9. Bend the straws downward. 10. Gently press in the middle of the stretched balloon and watch what happens to the water. Explanation: You created a pump that acts like you heart does. The neck of the balloon taped to the straw acts like a valve by letting water out through the straw, but not back in. In a similar way, your heart s valves allow blood out of your arteries. This jar represents one chamber in your heart. Your heart actually has four of these chambers pumping blood. Try it! What happens when you take the balloon neck off of the straw? Fun Fact: The blue whale has the largest heart of any animal. It weighs 1,500 pounds!

9 See Your Pulse Human Body minutes In this activity, students will be able to see their heart! Or at least see how fast it s beating. Materials Needed Per student: 1 glob of playdough or clay 1 toothpick 1 pen and piece of paper to record results A few per group: Stopwatches Steps: 1. Make a small ball with a little bit of clay or playdough. 2. Insert a toothpick into the ball, making sure it is held securely. 3. Find your pulse on the inside of your wrist, just below your thumb. 4. Stick the ball to that spot on your wrist, with the toothpick sticking straight up away from your wrist. The ball should stay on your wrist without being held there. 5. Watch the toothpick move as blood pumps through your wrist. It is now a visual indicator of your pulse. 6. Using the stopwatch, count how many times the toothpick wiggles in 60 seconds. That is your pulse. Write that down as your resting pulse. 7. Remove the ball and toothpick from your wrist. 8. Jog in place, do jumping jacks, or engage in some sort of high intensity exercise for two minutes. 9. Quickly put your ball and toothpick pulse indicator back onto your wrist and measure your pulse again for 60 seconds. Write that down as your exercising pulse.

10 Explanation: Every time your heart pumps, it sends blood through your body. The speed that it pumps is called your pulse, usually measured in beats per minute. When you exercise, your muscles need more food and oxygen from your blood so your heart has to work harder and pump faster. Fun Fact: Your heart pumps about 100,000 times per day!