What in the world did I do before Google Drive? Seriously? How could I have taught at all before? I use this for both personal and professional writing, statistics, storing, and sharing. The collaboration is insane in Drive. This would have to be my #1 pick if I could only have 1 app for the rest of my life (just don't ask me to do that!). Being a Google Apps District is a blessing!
ClassDojo was a saving grace for me! It is the perfect classroom behavior tool. I can reward for positive and negative behaviors. The students (and parents) can access their accounts and track behaviors. This was a great tool for IEP, CAT, and other meetings to have real accurate data on a student's behavior. If you have not tried this, it is a classroom app I won't teach without!
I don't know about you, but my online/digital life can become quite a mess. Where do I store all those great ideas, links, sites, info, and things I want to look at later? Before Evernote, they were everywhere (which really meant lost). Now, they are all in 1 site. I log in, go to a notebook, and Ta-Da! There it is. The Web Clipper tool is my favorite part of Evernote. I can clip for later viewing any web site and it saves links, images, and everything. This is great for organizing personal and professional lives!. 
Educreations is fantastic in the classroom on 2 levels. Most teachers use it to make record-able white boards. This is great for the flipped classroom. It allows students to go back and see a lesson again. My favorite part is the student side. Once you set up a class, your students enroll. Then, every whiteboard they make ends up in the class under the student's name. The teacher then can assess, review, and re-watch the student explain something. This is fantastic for assessing student understanding, right from your couch!
What can I say about Twitter...? It IS my PLN. I have learned more from the educators I follow on Twitter than anywhere else. It is connecting, learning, collaborating, and helping all in 140 characters. If you follow the correct people, the sky is the limit for what you can gain/learn. Don't forget about all those Twitter Chats to participate in! 
Flickr is a great site to store images. Most people know that. But, as a teacher you can take it a step further. Flickr allows tagging of images and sets. First, put images into sets (groups of images such as Science, Math, etc). Then, tag individual images with CCSS or content. Then, allow parents, community, the world to see how your classroom is learning the CCSS! Search for a standard and see it being taught in your room!
The invention of the phone is great, but what teacher can actually answer one? You can not stop teaching to return a call during the day, and when you get home you often don't want your personal cell or home number being seen by all parents. Here is where Google Voice comes in. Create a Voice number and give it to your parents. They call it. The message goes into your Google Account (you can have it forwarded to any number, email a transcript to you, or use the app on your phone to manage messages). Then, you can call parents back from your cell phone (or any line set up) and the parents only see the "Voice" number! No late night weekend calls from parents on private lines! J...U...S...T......A...W...E...S...O...M...E!.
My days of flash drives and emailing myself files have been gone for years! Dropbox is absolutely a Must-Have!. Any files in Dropbox (like your Documents folder on you PC/Mac) are synced to the cloud, and then to any device you have connected. What does this mean? If you have 5 computers/tablets, and create a newsletter on 1 of them, within seconds that file is synced, updated, and available on all devices. Wow! I mean...really...WOW! No more forgetting a file at home/school. Everything you create is where ever you need it. Even on a friends computer you can log into the web version and retrieve a file to share (not to mention just making folder/files shared with multiple Dropbox and non-Dropbox users!).
This is one of the easiest assessment/Exit Ticket apps out there. Simply create a quiz (multiple choice or short answer) and turn on the Teacher app. Give students a web based device (computer, tablet, phone) and go to the app or web site. Give them your classroom number, and take a quiz. Done! Socrative grades the assessment for you and gives the results back to you in an easy to use Excel spreadsheet! What could be easier or quicker? Give it a shot! 
They are everywhere! QR codes. Sure, they are great ways to get people to web sites. But...what about even better uses? Create audio or video files in your Google Drive and share the link that way! Then, the QR code opens streaming Audio! Put this code on a student's writing project having them reading it to the reader/listener! Attach the code to an art piece with the artist's explanation of their technique! Millions of uses beyond just a shortcut to a site!
Well...there you go. As difficult as it was (and believe me the list changed many times before I clicked "Publish") there is my list of "My 10 Essential Classroom Apps"! Whew...maybe I should have made it 20? That would have been easier!
Well...there you go. As difficult as it was (and believe me the list changed many times before I clicked "Publish") there is my list of "My 10 Essential Classroom Apps"! Whew...maybe I should have made it 20? That would have been easier!