I am a 1st grade teacher, so I will highlight 21st century tools that I think would be beneficial to to first grade classrooms (as well as other grades). I will highlight: 1) An interactive math program that is wordless, 2) the 'flipped' classroom, and 3)An interactive website, "Brainpopjr.com".
1) A wordless math program: My sweet husband introduced this to me, through TED talks. How exciting that my husband, an education major, is part of my PLN! :) This is the link to a brief video that explains the 'why' behind the product, and here is a link to the actual interactive product. You can play on it and see for yourself how it works. It doesn't 'say' anything, rather you logically (through trial and error) discover how to solve math problems for this penguin. It allows students to develop an understanding of math concepts in a deeper way than previously accomplished through a teacher talking and telling them how to solve problems. The success rate/results seem impressive, and I'm excited about looking into purchasing this for my students.
2) A 'flipped' classroom: Our principal introduced this to us recently. This is the idea that you preview the main teaching concepts of the day before students get to school, the night or weekend before with brief online videos. You can make them yourself, or pull them from Khan Academy or other online resources, and they will pre teach what you would normally spend time in the classroom covering. This way, when the students are at school, instead of spending time doing that, you can allow them time to practice independently the concept taught. Thus, you are free to walk around and interact with them, discuss what they are doing, and more authentically monitor their learning than in the traditional method of teach at school, independent practice at home (where if a problem arises, they are out of luck because you're not there to assist) etc. Here is a link to a video on a 'flipped' classroom, introducing 1st graders on how to use "youtube" to access future 'flipped' classroom lessons.
3) An interactive website - "BrainPopJr.com" BrainPopJr is an interactive website that is perfect for 1st grade students. Many of the academic concepts that we cover for the year are available on this site. The site is set up so that you can select a topic that you are studying, watch a brief video (roughly 5 minutes or so) and then participate in activities, such as on-line quizzes (easy or hard), vocabulary lessons, jokes, drawing or writing activities, links to books and other resources where you can study this concept further, etc. The characters in the videos are engaging for the students, and the videos are able to bring to life concepts in a more powerful/memorable/understandable way through sound, sight, movement, example, etc., than just I as a talking teacher could do. It has free videos that the students can access at home, or they can subscribe for a membership, as you can do as a teacher (or a school). It's well worth it! It covers all academic fields, not just science, but math, reading, writing, arts, etc. Here is a link to this resource.