This page lists online resources for teaching math through problem solving. The first section lists problembased curricula that are available for free, online, and the second section lists resources to find good problems.
Problembased curricula:
Elementary:
Middle:
High:
Where to find good problems:
 This website contains over 200 different patterns. It gives the first three or four steps and will give you the number in step 43. The site also has a great sheet for working out the equation. It has the students draw the next step, fill in a table and finally work on the equation.
 One good practice is to have students engage with the patterns purely visually, before they start to count things.
illustrativemathematics.org
 You can find problems organized by the Common Core Standards. Each problem has an explanation behind how the problem fits the given standard as well as a pretty thorough solution.
 This year they have compiled a curriculum for 6, 7 & 8 grade. They have lesson plans for each unit with investigative problems.
State of Georgia's Common Core  Many tasks for different sources and compiled them into units
math.mapshell.org
 Many investigative projects and they rank them from novice to mastery of different topics
 It is divided into 6, 7, 8 and then High School, and then split into different standards.
 The lessons here are usually designed around an open ended and interesting problem that students are trying to answer. They include openended questions that you could ask to students if they demonstrate certain misconceptions.
 I use a lot of these lessons to start out my units it allows me to expose students to an interesting problem where the math we learn in the upcoming unit will be useful.
LearnZillion
 you kind of have to dig to find rich mathematical tasks
NCTM Illuminations
 Like anything, there are good, wonderful, and "enh" activities on it. At times, I feel that they are a little bit lower level in terms of "doing mathematics" goals, but make useful jumping off points for many ideas. I would definitely consider it a good resource location.
betterlesson.com
 Database of a number of teacher's lesson plans
 They have "master teachers" who have some great lessons for problem solving
 I turn to betterlesson.com a lot if I'm stuck on a particular standard, or I'm unsure what unit to cover next.
Dan Meyer's Three Act Math blogs (http://blog.mrmeyer.com/2011/thethreeactsofamathematicalstory/).
 You can even search through them by standard which I find really helpful.
 I also just find his approach really inspirational for helping me to see problem solving ideas all around me in the world!
MCTM Math Contest website. https://www.montanamath.org/?p=contest/tests
 They have examples of old tests, which feature really great problems!
https://whenmathhappens.com/#
https://emergentmath.com/
 Problem based curriculum maps!
http://www.insidemathematics.org/problemsofthemonth
 Lots of problems of the months that are divided into different categories depending on what you want to focus on.
 Each problem has different levels within each problem. You are able to just give a single level or do the problem over a course of a week or more and do multiple levels because they build off each other.
www.mathteacherscircle.org
Popular press
 I often pull things from articles that I've read in various places  the fivethirtyeight blog, New York Times, Washington Post, our local paper etc. Sometimes the best things I find are about people using statistics poorly, misrepresenting results, poor graphical displays, etc. which lend themselves nicely to lively discussions in class.
 538 is such a rich site for students  I like that it has so many different types of statistical articles, from sports to current events to political issues. I have used it as a resource in AP Stats, but I am planning on having students search out their own data on it more often in the future to practice analyzing information.
American Statistical Association website more  specifically the Statistics Education Web (STEW) section.
Rossman chance applets (http://www.rossmanchance.com/applets/)
breakout.edu
 Students get different tasks, clues and problems to solve in order to unlock the box.
 You can design your own task or choose from a variety of tasks created by other teachers.
 The password for the whole site is : showyourwork
http://www.mathematicsvisionproject.org/
 These tasks are created for a block schedule and an integrated approach so I really have to pick and choose what parts I will use from each unit but they are great problem solving tasks and scenarios.
 They also have a "Ready, Set, Go" portion where students practice what they learned and practice/review older concepts as well.
 These guys do offer an entire curriculum, any school that is thinking about buying a new book should contemplate using MVP and spending the money on professional development!
MathPickle.com
 The founder, Dr. Gord Hamilton, is a brilliant K12 puzzle and problem designer. His problems often look like a game or puzzle, but there is always great mathematics at the heart of the problem. I have done so many MathPickle problems with my students. They love them and there is so much engagement and exciting during the problem solving process.
 For a MathPickle problem, I often create some slides based on the problem and try not to overexplain the problem. I want to set the students to exploring with the hope of inviting clarifying or expansive questions about the problem. For a MathPickle game, I usually play a truncated version of the game (class vs. teacher), so we agree on the mechanics of the game.
Julia Robinson Mathematics Festival (www.jrmf.org)
 a nonprofit whose mission is to promote K12 student joy and interest in deep mathematics. Their problems tend to be low floor, high ceiling through the use of increasingly difficult levels of the problem. On their website, they share a number of their festival problems. I highly recommend using manipulatives in combination with the problem if possible. It makes the problem more accessible for all.
Numberplay
 This was a weekly math puzzle blog that ran for ~7 years in the New York Times. A guest writer would pose a problem/puzzle for the week and then interact with readers in the comments section of the blog.
http://www.rpdp.net
 Many of the available resources are traditional in format but I have found quite a few that have excellent problemsolving components.
