Sesame Street has produced a number of segments about environmentalism.

Picture Earliest Known Appearance Description
Episode 0514 Mr. Hooper, Luis, Maria, David and Bob all throw a small amount of litter on the ground, adding to the street's filth. When a voice asks "Who made this mess?" each one of them denies that it was them, saying they only dropped a small amount of garbage on the street. The voice then tells them to put the trash in a trash can instead of on the ground.

Episode 0811 Part 1: In a park, a garbage man puts litter in a trash can.

Part 2: A man reads a newspaper, then shamelessly drops it on the ground. A little girl finds this disgusting, and puts the newspaper in the trash bin.

Episode 0811 Gordon and Bob have picked up some items which they think Oscar would like, such as old tires and straw. However, Mrs. Romo shows them how to re-use them: the tires can be cut up to make a feeding trough, or a basket, or a pair of sandals. The only thing they can find for Oscar is a chewing gum wrapper.
Episode 1049 A fisherman becomes frustrated with all the seaweed he's catching instead of fish. To cure his woes, he removes the surrounding plant life, but still doesn't catch any fish. A clam informs him that by removing the fish food, he's disrupted the ecosystem. No food: no fish.
Episode 1578 Gordon preaches the importance of rain as it starts to do so in his office.
Episode 1839 A man learns that it's better not to pick the flowers.
Episode 2627 A girl narrates a film about how paper can be recycled. She gathers some comic books and newspapers into a wagon, and takes them to the recycling center. From there it is sent to the mill where it is washed, pressed and rolled into new paper. Hulu
Episode 2718 Two-Headed Monster finishes a bag of popcorn, and almost leaves it on the brick wall, but then argues over which trash can to throw it in. Finally, it rips the bag in half to "share" the trash.
Episode 2726 The Two-Headed Monster finishes drinking milk, and doesn't know what to do with the cartons at first, but gets the idea to "recycle" them and play with them like a train.
Episode 2746 Frank the fish calls Carl and tells him not to leave the water running while brushing his teeth, otherwise the lake will be dry.
Episode 2755 The story of a cat who hated rain, wished for it to stop, and witnessed the disastrous effects of no rain.
Episode 2762 Three mayonnaise jars follow three different paths after they leave the factory. One jar was reused as a coin bank, one was used as a home for tadpoles and the third was taken back to the glass factory to be recycled.
Artist: ArtistMike
Episode 2781 Gloria Globe appears sick and ailing, because of pollution and damage to the planet. Only by taking better care of the Earth can Gloria become well again.
Episode 2784 In the environmentally conscious portion of the program, Oscar the Grouch is about to make a new sign that says SCRAM, when Telly Monster shows up and points out that he left his record player on, so he turns it off. Telly compliments him for not wasting electricity, and then points out that he can make a new sign by writing on the back of the old sign, which saves cardboard (and trees). Oscar hears the water dripping, and knows exactly what Telly's going to say, so he beats him to it, and then tells Telly to stop wasting his time and go away.
Episode 2839 Leanna WIlliamsmust save the world by cleaning it.
Artist: ArtistMike
Episode 2946 A little girl narrates a film about how cans can be recycled. She washes them and collects them in a wagon, which she takes to the recycling center. There it is sorted and separated with a magnet. After its loaded onto trucks, it is taken to a factory to be melted and shaped into new cans like the ones seen in her fridge at home. Hulu
Episode 2962 The Martians spy a leaky faucet through a kitchen window. As it continues to drip, a Fat Blue woman turns it off, shocked to see that she had been wasting water.
Episode 2973 Three frogs say "reduce, reuse, recycle!" and hop around the globe.
Episode 2973 A boy who lives in Bali narrates a film about how his community recycles their resources.
Episode 3001 Super Grover crash-lands inside an apartment, and when he sees that the lamp light is on, he decides that he needs to save energy by turning off the lamp. His method to turning off the lamp is blowing the light out like the flame of a candle, but a girl just turns off the switch.
Episode 3002 The Adventures of Prairie Dawn: Prairie Dawn turns off the television to save energy.
Episode 3086 Determined not to litter, Prairie decides to throw an empty box into a trash bin, but it runs away from her.
Episode 3141 Cartoon aliens vacation on Earth for an afternoon, but they litter.
Episode 3241 Monsterpiece Theater: Conservations with My Father, introduced by Alistair Cookie, who makes a wardrobe change to star as his usual self. Cookie Monster's Pop teaches his son about saving water by turning the faucet off tightly and saving electrical energy by turning off the TV when nobody is watching it. They spy a plate of cookies and decide that those shouldn't be wasted either, but Chef John and a group of monsters rush in to admonish the pair for eating the cookies which they were saving for themselves.
Episode 3698 Noodles and Nedd: Nedd feeds Noodles candies and teaches his cat not to throw the wrapper on the ground, but to throw it the trash bin instead. When they have moved on and can't find a garbage receptacle, they overfill their pockets until they use a surfboard with a motor to go home and throw their trash away there.
Episode 4060 Global Thingy is bombarded with litter and pollution. Other thingys clean him up.
Episode 4177 Bert and Ernie's Great Adventures: Bert and Ernie teach a beaver to not cut down trees, as animals live in them and their homes will be destroyed.
The Super Morphin Mega Monsters encounter a girl in the park and show her where she can throw away her litter.
After Abby finishes coloring her paper, she plans on throwing it out. Elmo has different plans for it - he recycles it into a paper airplane for them to play with.