So if … critical thinking is “the intellectually disciplined process of actively and skillfully conceptualizing, applying, analyzing, synthesizing, and/or evaluating information gathered from, or generated by, observation, experience, reflection, reasoning, or communication, as a guide to belief and action (, then this is not it …
According to the IBO’s learner profile “definitions”, a thinker is someone who exercises initiative in applying thinking skills critically and creatively to recognize and approach complex problems, and make reasoned, ethical decisions.
In a nutshell, critical thinking basically means “use your brain.”
Take a look at this math problem, and see if you can figure the student’s “thinking.”
Mathematically speaking, the algorithmic way to go about this would be to solve the number model as 12 + (6 x 11) + (2 x 10) = 98 but that involves procedures that are not developmentally appropriate for a seven year old.  Instead, this student used her “critical thinking” skills to partition numbers in a way that makes sense to her (for example 12 = 10 +1 +1) and then adding up all the tens and then the ones.  It works and, more importantly, the student can reason and explain why it is so!
So what does this mean for me as an educator?  If you believe, as I do, that our responsibility is to prepare students for the “real world” so that they can solve problems independently – then our students need to be able to think conceptually
– because solutions are not always going to be “algorithmic” with a logical series of steps to follow in order to reach “the answer.”
A good starting point therefore is a concept-driven curriculum, whereby students construct their own meaning through critical thinking and the transfer of knowledge across disciplines.  This is where the PYP inquiry framework really shines, by allowing students the possibility to learn deeply through the lens of key concepts as opposed to covering content in the form of isolated factual knowledge or discrete skills.

The International Baccalauraeate Organization states that “in order to become successful learners, it is necessary for students to feel empowered by their learning, to value and take responsibility for their learning, to demonstrate resilience and to develop independence. Such learners are able to reflect on themselves, their experiences, and the process of learning in order to support personal growth and their ongoing commitment to personal, social and physical well-being.” (PSPE Scope & Sequence, 2009).

What this means in practice can best be illustrated by way of example … imagine yourself as a pedestrian waiting for the signal to turn green.  When it does eventually turn green your “algorithmic” response is to cross the road because in our mind green means it is “safe” to do so.  However, because of past experiences in your life your brain is constantly adapting and making connections and tells you to first look both ways just in case (think that mom voice in the corner!)  Sure enough a distracted driver didn’t see their red light telling them to stop and so … accident averted for now because you were able to use your critical thinking skills!  (As an aside, next time you are crossing a road make it a point to notice how many people are just blindly walking across on the assumption that green means it so safe for them to do so).

So though I don’t have specific advice to dispense, generally I do believe that we can help our students to become critical thinkers by allowing our students to purposefully inquire into their world by making connections across subjects and disciplines, and allowing them to apply their new learning and skills across different contexts – and no better context than with real world applications!
In terms of  how to assess critical thinking skills – easy – you know you will have been successful if your students look both ways before crossing the road with their Pokemon Go in hand!  The epitome of a lifelong learner! =)