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We have been thinking about effective ways to teach and consolidate Newton’s 3rd law of motion and in particular we have focused on an example that often causes a lot of confusion among learners and (sometimes) teachers – an object at rest on a table. The question is “what are the forces acting on an apple at rest on a table?” followed by “are these forces an example of Newton’s 3rd law pair of forces?”

We have embedded the mind map below to illustrate a possible sequence of activities that might help learners to understand this problem, hence, consolidating their knowledge and understanding of Newton’s 3rd law. The mind map is explained in more detail below.

 

The mind map above is intended to be read clockwise starting from the ‘Knowledge‘ branch. Here we outline the prior knowledge we would expect a group of yr11 students (15-16) to have before this series of activities.

The ‘Sequence‘ branch points out that traditionally Newton’s laws are taught starting from the 1st law and moving to the 2nd law and then the 3rd law. This is usually reflected in exam board specifications. However, we suggest that a more logical sequence could be to start from the 3rd law, then 2nd and 1st. This is because our proposed sequence goes from more general and universal interactions to more specific cases of forces. Let us explain what we mean here. Newton’s 3rd law deals with the interaction between two objects and it explains the universal truth that forces never come in isolation, but that every force has an equal and opposite force which completes the pair. This is often referred to as “for every action there is an equal and opposite reaction”. However, the last statement does not emphasise the fundamental point that for an ‘interaction pair’ in Newton’s 3rd law terms to occur there must be an interaction between two objects, so as object A applies a force on object B, object B will apply an equal an opposite force on object A. Newton’s 2nd law deals with the forces applied on a single object and this enables us to study how the state of motion of this object changes. In fact, F = ma accounts for the vector sum of all the forces on the object in question (the resultant force F) and essentially states that a resultant force different from zero will cause an acceleration on that object, i.e. its velocity will change. Newton’s 1st law is, therefore, a special case of Newton’s 2nd law for objects where the resultant force is zero. In fact, if the net resultant force is zero, the object is said to keep moving at constant velocity (if it was already moving), or to remain at rest (if it was stationary), i.e. its state of motion will not change.

The ‘strategy‘ branch outlines some useful ways to introduce the problem and to enable your pupils to think deeply about the problem of the apple on the table. So, at first we would give an apple to each group of students and ask them to put it on their table and stick some laminated arrows on the apple with blue-tack to illustrate the forces acting on the apple. Students are given arrows of different colour and size to encourage them to use their own ideas. For example, students who understand that the weight of the apple and the contact force of the table on the apple are two different types of forces (hence, cannot be an example of Newton’s 3rd law) might use different colours, but equal sizes to represent the forces on the apple. At this stage we encourage learners to share their ideas through group and class discussion. The role of the teacher in facilitating class discussion should be to paraphrase ideas expressed by students, but in a non-judgemental way, so that other pupils are not influenced by the teacher too early. The rationale behind this approach is to let students explore each other ideas and explanations, so that their own understanding of Newton’s laws can be challenged and they are forced to think more deeply about these topics, possibly reaching cognitive conflicts.

At this point it is useful to introduce the ‘language‘ in the fourth branch of the mind map “The force of the ‘thing’ on the ‘thing'” (we need to acknowledge the great Helen Reynolds here, as we were introduced to this language by her). This helpful and careful use of language enables the learners to focus on Newton’s 2nd and 3rd laws in more intuitive and logical ways. So, when looking at all the forces on the apple we identified two forces:

– The gravitational force of the earth on the apple

– The contact force of the table on the apple

This language helps us to clearly distinguish what type of force is applied, what object applies the force and on what object the force is applied (the apple). So, the two forces above cannot be an ‘interaction pair’ (Newton’s 3rd) because they are both applied to the apple and they are different in nature.
If we are looking at the interaction pairs in Newton’s 3rd law terms for the two forces above we would use the same language to say:

– The gravitational force of the earth on the apple

– The gravitational force of the apple on the earth

And for the contact for of the table:

– The contact force of the table on the apple

– The contact force of the apple on the table

It is useful to then introduce other examples of objects experiencing forces using a good mix of contact and non-contact forces and let the students use the language introduced above to identify the forces acting on these objects and discuss whether they are examples of Newton’s 2nd, or 3rd law.

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Aaron was only 10 when he introduced me to WordPress and blogging. It is thanks to him that this blog ever started, so it fills me with joy to be able to blog again about another great achievement of his in the world of technology.

Now that he is 16 and in the midst of his GCSE exams, he has developed his first game for the iPhone/iPod. This was his personal project that he set himself over the Christmas holidays. He was not prompted by his ICT teacher, nor set this as a homework from school, just his own interest in coding and developing something good and rewarding.

You can find his game, which is actually really good and, in my opinion, stands up there with the big viral and highly addictive games like Doodle Jump, Angry Birds and Flappy Birds, here. RFLKTR is a really engaging game that uses mirrors you draw on the screen to guide a laser beam through gaps in the walls it encounters as it travels in space. This really interesting and stimulating feature of the game, which sounds easy, but believe me it is really hard, makes it a really engaging tool for Physics teachers when teaching Reflection of light!

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At the moment the game doesn’t seem to work on the iPad, but I am sure a later release will fix this and I would love to have other features of light that could be used to guide the laser beam across the screen. For example, it would be awesome to have blocks of glass and other materials of different refractive index appearing every now and again so that the player could move them in front of the incoming beam as well as changing their angle, so the beam can be refracted instead of reflected with these special items, etc…

Please shout out about this game and download it, because I believe learners who take their own initiative to create something like this deserve to be recognised for their effort and creativity!

This post is a little out of theme, but my nine year old son was so excited when he discovered this glitch that I had to take a video and blog about his achievement 🙂

There are other glitches that allow you to duplicate your items on Minecraft PE, but we have not seen the one Matteo found this afternoon yet. The nice thing is that it seems his methods is much, much quicker than other methods we have seen on YouTube. So, please share this link and like the video, so his method can climb at the top of the search results.

To prove this actually works check out the diamonds blocks house he made in his world.

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I was playing a new update of Doodle Jump on my iPhone this morning and I suddenly thought it would make a pretty cool lesson on motion and it could actually apply to both GCSE and AS Physics, depending how you phrase your questions.

The idea is to find out how high the little alien in Doodle Jump actually jumps. There is no reference in the game to suggest what scale the screen has, so I used Vernier Video Physics and arbitratily set the distance between the block on which the alien was jumping (see video below) and the last but one block above the creature to be 10m.

I then tracked the position of the alien for one jump and the analysis of the velocity graph shows the gradient is not right, i.e. g is not close enough to 10m/s2.

So, I went back and changed the scale to be 4.5m between the two blocks mentioned above. That seemed to have done the

trick, as the gradient of the velocity – time graph in the video below is about 10m/s2.

If you look back at the Displacement – Time graph for the vertical axis, you can now see that the little alien jumps to a height of about 2.3m. That is quite something for a little fella like him.

Obviously, we are assuming the alien is jumping near the surface of the earth, or at least a planet with the same g.

2013 in review

Posted: December 31, 2013 in Uncategorized

The WordPress.com stats helper monkeys prepared a 2013 annual report for this blog.

Here’s an excerpt:

The concert hall at the Sydney Opera House holds 2,700 people. This blog was viewed about 15,000 times in 2013. If it were a concert at Sydney Opera House, it would take about 6 sold-out performances for that many people to see it.

Click here to see the complete report.

2012 in review

Posted: December 31, 2012 in Uncategorized

The WordPress.com stats helper monkeys prepared a 2012 annual report for this blog.

Here’s an excerpt:

4,329 films were submitted to the 2012 Cannes Film Festival. This blog had 21,000 views in 2012. If each view were a film, this blog would power 5 Film Festivals

Click here to see the complete report.

It was great to moderate the Twitter #addcym chat tonight as the topic that was picked was one I am really passionate about, i.e. Peer Coaching! We also had the privilege to have Les Foltos (@lfoltos), a World leader in Peer Coaching, joining the chat for a while and Stuart Ball (@innovativeteach) who gave some real experiential insights on the process of Peer Coaching as well as offering to run the course for teachers, and we hope to be able to take him up on that one 🙂

Another late contributor was Gavin Smart (@gavinsmart) who promised a link to his school’s video on the Peer Coaching GROW model.

There were so many contributions tonight that I am bound to omit something, so I will just give a list of the main points (according to my understanding of the chat) as bullet points!

– Some asked if the Peer Coaching process should be formal, or informal and there seemed to be a general consensus that Peer Coaching should encourage relationships of trust and non-judgemental support

– Some felt strongly that Peer Coaching shouldn’t be tied to Performance Management in order to remove the “fear” of failure and judgement. The main reasons behind this view seem to spring from the need to let the individual teacher identify targets according to their needs and interests. A set of targets prescribed from the top differs from coaching because it does not encourage reflective practice some felt!

– This led to the view that Peer Coaching should be a bottom up process, initiated by the Coachee and facilitated by the Coach. Some also identified the need to have the full commitment of SLT in terms of time and funds allocation in order to make Peer Coaching genuinely effective. Some believed that without SLT full commitment to Peer Coaching only the enthusiasts will take the lead and this would not bring whole school improvement, but only pockets of good practice!

– A good model was given by Gavin Smart’s School (Priory Community School) where “Half of all staff attend the GROW program during twilight inset at PCSA focusing on using coaching with students and staff” suggesting that a large percentage of CPD dedicated time is committed to Peer Coaching!

– Another interesting thought that was raised was whether the Coaches should be the “Experts” or ordinary teachers. This divided the discussion a bit into those who see the need to have technology savvy Coaches that are always ready to offer support and solve problems and those who believed that an “Expert” could be too threatening for some Coachee and inhibit their process. In particular, some were concerned about the potential danger that “it’s too easy to get the coachee to do what you do, rather that letting them identify their own needs”. I believe behind these reflections there is the fundamental question to be asked: “What is the role of a Peer Coach?” Les offered some truly refreshing and useful insight on this point by saying about Coaches: “Not expert with answers. Raise questions, provide support encourage teachers to solve issues. ” I am inclined to agree with this view, because if the Coach plays just the part of the expert and if they have a solution to the problems the Coachee is facing always ready, who are they encouraging the Coachee to engage in reflective practice? And without reflective practice how can the Coachee make real progress and learn to walk on their own?

– Latching on to the last point someone suggested that it is important that the Coach becomes the Coachee at some point in the Peer Coaching process. In this way the circle is closed and the “Expert” complex can be avoided.

– Some other really valuable contributions included the idea of Coaching Learners and having Learners Peer Coaching each other and/or Peer Coaching teachers. I see that idea similar to the many examples of Digital Leaders that are beginning to surface in many schools these days. Some felt that some teachers would resist the idea very strongly and feel quite uneasy about it!

I hope I have given a good account of the discussion, but feel free to correct me and add things I have missed out. Please continue the discussion in this Forum Thread on TES.

via AnswerGarden: What Science Skills should be promoted and developed on TES?.

I am finally finding literally 5 minutes to catch up with a few things I have been doing since the beginning of the term and I wanted to share with you how I am using kidblog.org to create collaborative feedback between different schools and cross-phase. Our Yr12 Blog is here.

I believe allowing our learners to Blog is a powerful learning strategies for a number of reasons. Firstly, our students get a real audience and are more likely to take their assignments seriously and be enthused by the thought of communicating their work to the world. That is why it is so important for them to see comments appearing on their posts, as they get the feeling that their efforts are appreciated by others! Also, comments are a powerful and simple means to peer assess each other’s work, as well as, obviously, for the teacher to leave some feedback too.

So, I introduced my Yr12 to our CroesyPhysics Blog and set a couple of assignments for them. The first is something I have been doing for the last couple of years and it is about the learners writing poems to describe the Photoelectric Effect, more about it on this previous Blog post. But the second was a collaboration between our Yr12 learners and a Yr6 class  at Highlawn Primary School. In these Blog posts our learners had to explain energy levels and photon absorption and emission to an audience of 10 year old pupils. You can read the Blog post to set the assignment here. Our Yr12 students could present this Physics topic in whatever form they wanted, but it was very clear to the majority of the Bloggers that they needed to find a way to get their message across in a simple and coherent way, and that they could not assume anything, not even that the Yr6 learners would know what an electron, or an atom is!

So, I gave them a link to the PowerPoint I would have normally shown them on the topic and told them to use that and their text books to gather the information they needed to support their creations. I was pretty confident they would not copy and paste, because if they had, they would have failed to be understood by the Yr6 learners, who are reading our Blog posts and leaving comments to feedback on our students’ presentation, clarity and accuracy. It must be said that the comments we have had so far are really thorough and very well written for learners of that age! Learners at Highlawn Primary certainly know what it means to reflect on learning.

I think we’ve had some really good Blog post so far and this excercise has been useful for our learners, but I would love to hear your opinions and if you can spare a couple of minutes, please read through some of our learners’ work and leave a comment for them here! They will be thrilled to see others value their work.

In my previous post I showed the first part of my boys’
story mind map, i.e. the mind map we designed together to tell the story they
were creating. We used iMindMap 5 because we wanted eventually to narrate their
story by recording audio comments on branches. That turned out to be a really
effective and creative process. Having the mind map as their main structure for
the story allowed the boys (4 and 6) to not only see the whole picture, but
also to break down the story in little chunks that they could narrate very
easily. In fact, on each branch they could record their voices narrating what
the branches represented. This was telling the story itself and by playing back
each branch’s audio comment they could listen to their story and show Mamma
(Italian for Mum) their creation and impress her!

We couldn’t upload the new version of their mind map (with
audio comments) on Biggerplate, because it is too big, but you can watch a video of their narrated story below.

I believe that this process could be extremely useful in
story writing, as it helps learners to design a coherent story and see how the
whole story unfolds in their mind map, as well as splitting the story into
branches that the learners can narrate. It will then become very easy to
transfer their story from their iMindMap 5 audio maps into paper, or a blog!

Please, leave a comment to my boys mind map, as they will be
very pleased to see others appreciate their work!

Thanks!!!