Thanks to today’s Google Doodle, I was reminded that it is Earth Day. The day was commemorated in 1970 to bring awareness to the damage being done to our environment. To further this message, notable companies like Apple and Microsoft have implemented plans to reduce their carbon footprint and use more renewable energy. 

If you’re looking to get involved and do your part today, look no further than your home, school, office and the many other places you visit daily to help out our environment. The possibilities are endless, but one of the most common options is to recycle.

According to the Environmental Protection Agency, recycling can help conserve natural resources and energy, generating over $37 billion in wages. So in honor of Earth Day, let’s have a bit of fun and put your recycling knowledge to the test. 

Read more: Go Green and Save Green With Top Earth Day Deals on Eco-Friendly Products

Note: Recyclable items may vary by location, so check with your local recycling center or government agency if you have questions.

To recycle or not to recycle? Let’s put your knowledge to the test

Pizza boxes?

Yes, according to the EPA, even grease-laden boxes can be recycled. However, food scraps like uneaten crusts must be removed, and boxes must be flattened.

Hardcover books?

No, hardcover books can’t be recycled. The covers are usually made of different materials, including plastic and leather, which aren’t recyclable. The glue that binds the books together can be hard to separate from the pages as well. Instead of recycling a hardcover book, try donating it to a school, library or nonprofit organization. Donating books can help people increase their vocabulary and improve their communication skills. Plus, it’s a good way of making more room on your bookshelves.

Paperback books?

Yes, you can recycle paperback books, even if they’re beyond repair. Like hardcover books, you might want to consider donating the books if you want to get rid of them. 

Batteries?

Yes. According to the EPA, lead-acid batteries are among the most recycled items, including car batteries. However, batteries require special handling, so they must be recycled at separate locations and can’t be recycled in your home recycling bin. This tool can help you find a location to recycle your batteries.

Receipts?

No, you can’t recycle receipts. Most receipts are coated with Bisphenol A, a plastic compound more commonly known as BPA. This compound makes the receipts unrecyclable, and it could be bad for your health, according to the Mayo Clinic. The best way to dispose of receipts is in the trash, but you might want to shred the receipt before throwing it away for financial security.

Stickers?

Stickers can be fun, but unfortunately you can’t recycle them. The glue that holds stickers in place can gunk up recycling machinery, and some stickers, like vinyl stickers, can be harmful to the environment.

Carpet?

Yes, carpet can be recycled. Nearly all kinds of carpet can be broken down and used to make new products, and the complex fibers of carpet make it nearly impossible to break down in landfills. However, the infrastructure required to recycle carpet isn’t widely available, and you can’t put carpet in your home recycle bin. The nonprofit Carpet America Recovery Effort is one group working to put the necessary infrastructure in place to recycle carpet everywhere. For now, use this tool to find a location that will recycle your carpet. 

Motor oil?

Yes. Many garages and auto shops recycle your old oil when you take your car in for an oil change. If you perform your own oil change, these same shops will usually accept oil for recycling. Like batteries, motor oil should not be put in a household recycling bin. The used material from one oil change is enough to contaminate one million gallons of fresh water according to the EPA. Use this tool to find a location that will recycle your used motor oil. 

Compostable plastics?

No, even though they’re made from renewable materials, like corn, cellulose and soy protein, compostable plastics can’t be recycled. «Compostable plastics aren’t meant to be recycled and can contaminate and disrupt the recycling stream if mixed with non-compostable plastics,» according to the EPA.

Wrapping paper?

Trick question — yes and no. Shiny and laminated wrapping paper can’t be recycled, but there are recyclable wrapping papers available. The EPA says a recyclable wrapping paper alternative is newspaper. Plus, using newspaper as wrapping paper gives the gift recipient something to read while they wait to open their gift.

Bonus round: Aluminum cans?

Yes, empty aluminum cans can be recycled, but the cans can’t be crushed. The EPA says that crushed cans are harder to detect when being sorted within recycling facilities. All those TV shows and movies that show people crushing cans to take to the recycling center lied to us. 

Read more: You’re Recycling Wrong. Stop Crushing Aluminum Cans

For more, here’s how to recycle old tech and gadgets for free, why you don’t want to hoard your old tech and how plastics recycling misses the point.