Grade 2 – How The World Works – Forces

Grade 2 inquire in to forces and motion in their classroom and in PE to make connections to games and equipment.

Central idea: Investigating and understanding scientific principles allows people to innovate and create.

Key concepts: Form, function, reflection           Related concepts: Striking, energy transfer

Lines of Inquiry: 1.  Force and Motion 2. Design thinking 3. How research influences scientific understanding


In order to make the most meaningful connection to the learning the students are undertaking in their classroom whilst engaging in PE, I have decided to focus on the first line of inquiry relating to forces and motion. Examples of these scientific principles can be observed in just about every sport or activity, and by focusing on this area in PE, the students will hopefully gain a deeper understanding of the central idea.

I wanted this session to essentially highlight two basic principles relating to the concept of force, those being a pushing or pulling force. So we began the session by dividing up in to house teams and competing in a round robin of tug of war battles. Following a number of matches we had a water break and discussed the games and I began the session by simply asking, “What was hard about the match?” This led to a number of responses all of a similar nature: how hard it was to pull the other team in the opposite direction. As the students had already tuned in to this unit in the classroom, I asked them to make any connections to their unit, leading to responses about the lines of inquiry and how they were, “Investigating science stuff, like forces and energy.” The video below was a great battle which, which got the rest of the class cheering loud.


I asked the students to think about the other examples of pulling forces in sport and the students were able to list a few like: swimming, weightlifting, arm wrestling and rowing. I then asked them to think of the opposite and there were numerous and clearly more evident: baseball or striking any ball, basketball, tennis, martial arts, volleyball…the list went on a little. I had wanted to introduce a new game to them called Monster Ball which I had seen online from a PE teacher known as the PE Specialist, Ben Landers. He has an amazing website with loads of great ideas which can be found here:

Monster Ball sees the students use one ball (medium size/soft) to throw against another larger exercise ball in order to make the large exercise ball move. The aim is to try and knock the ball to the opponents side and out of the playing area, essentially forcing the large exercise ball towards them as they try and repeal the ball and send it the opposite direction. This requires the students to constantly run and retrieve their ball after throwing it against the target ball. It is important to implement a few simple rules such as: students may run in to any area they want to retrieve their ball but they must not ever touch the large exercise ball, especially to stop it from crossing the line. Other than that, the game is fairly easy to understand once it has been viewed, so I think I’ll just let the video do the rest of the explanation.


Here’s a different perspective. Ideally, the ball could just be left alone to go out of the area wherever it happens to go out, but we said we would push it back in if it looks like it’s going to go out of the area across the middle/starting line.


We played a full round robin competition of these matches so each house team got to play a number of times against the other house teams. Following the matches and before leaving, we reflected on Monster Ball and the forces of pushing involved with some astute students observing how it uses a similar style of play to snooker/billiards, in that you use one ball to strike another target ball to make that ball move. I explained that we would continue to engage in some similar games/activities in order demonstrate and highlight the forces and motion in sport and PE which includes a future field trip!


Session 2

This week’s session will begin a run of mini experiments where I try to create a physical activity that aims to highlight scientific principles related to forces and motion. To begin, I decided to go as simple as possible and use a well known relay race to get students moving and thinking. To try and connect with the unit and focus on forces and motion, the students were asked to race the relays while pushing a ball with each race introducing a new and heavier ball. The students were divided up in to their house teams again and began the first race with a table tennis ball, then the second race involved a tennis ball, then a medium size soft ball, the fourth race used a basketball, the fifth a light weight medicine ball before the heavy medicine ball. Below is a mix video of the different classes going through the various stages.


We held small discussions between each race as I asked the students to make observations and comments regarding the forces and motion in play during the races. The response was great from the students who covered a wide range of areas from pushing forces, the differences between the bounce or non bounce of balls, solid and pumped balls as well as more scientific terms like speed, acceleration, momentum and friction. Whist it is entirely possible for a grade 2 student to have come across these terms outside of this unit, I know they have been discussing various scientific terminology in their classroom and aimed to reinforce them in my PE lessons, so it is clear we are already having some examples of trans-disciplinary learning and sharing taking place. With a little bit of time left, we decided to have a few more rounds of the tug of war to see if we had some different winners to the previous week. To keep the students thinking afterwards, I asked them to consider what was more important for the tug of war: speed, acceleration, momentum or friction.


Session 3

As mentioned, this session would be another mini experiment but this time I wanted to try a session in the pool. The students take swimming lessons as part of the PE program and I try to view the swimming pool as another venue to continue learning within the unit. Therefore, I created a few experiment focusing on forces and floatation/buoyancy. The idea was for the students to take turns working in pairs to try and submerge a kick-board for 10 seconds. The students would have to consider and rate how hard it was or how much force they used to submerge the board. Following the first board, I added  another board so the students would have to submerge two kick-boards in the second round, doubling the buoyancy from the first. Each round then continued to add a board until we ran out of kick-boards at six, which was actually too much and too hard to keep submerged in the end. The video below is once again a mix of the increasing stages of submerging kick-boards experiment.


Similar to the previous week, we held small discussions in between each round and discussed as many principles as possible. The students were a little less sure of the terms relating to water and began by stating things like, “It wanted to bounce out of the water” or “It has energy under water”. The term pressure did come up after prompting them with a question related to what it felt like to swim deep under water and some students commented on how it was easier to turn the kick-boards edgeways at first, but after there were many, it was harder as they all wanted to pop out. The session seemed to be a success as the students discussed the experiment as they walked to get changed with some students commenting on how they might “Do” this experiment for their summative assessment task as they will be holding a Science Fair to demonstrate their knowledge and understanding of the central idea in any way they choose, so that was an encouraging end to the lesson.


Session 4

In this session we returned for the pool for another mini-experiment. As the experiment was not that long (10-15 mins) we broke up in to two groups, one to practice swimming with out teaching assistants and the other to do an experiment with me before swapping over. Before we began we discussed the previous pool experiment where we explored forces in relation to buoyancy with kick boards, trying to push them under water. I explained that in this experiment we would be reversing the action and focus on pulling or lifting weights from underwater to above the water. For the smaller weights, I had a 500 gm and a 1 kg discus. Then I moved up to a 2.5 kg weight, a 4 kg ball and finally an 8 kg ball. The groups moved around to the different stations, trying to initially lift them from the bottom of the pool to the water line and then up in to the air. I asked them to observe the differences between lifting the different weights from under the water as well as the difference between lifting under water and above the water. Below is a mix video of the students in their different stations taking turns to test the different weights out.


Following the experiment, the students dried off and came over to an area where we have a whiteboard set up on a wall. I asked them to discuss the experiment and simply exchange experiences before we discussed as a group. There were many students once again who were quite astute with their observations and most agreed that it was much easier to lift the object under water compared to above water, and this became more evident (it got harder) as the weights increased. Comparing the lifting underwater was a little more disputed. Some said it was easier whilst others felt there was not much difference. between them when going from one stage to the next but if you went from the 500 gm discus up to the 8 kg ball, you could tell the difference even lifting underwater, however once they were out of the water, the 8 kg was much harder to lift in to the air. I then shared the following information with the students which is a scientific principle they will follow up on in their classroom:

Archimedes discovered the scientific principle of buoyancy which holds that an objected submerged in water displaces water according to how much it weighs. In fact, the water will push upward against the object with a force equal to the weight of the water it displaces. Source:

So breaking this down to the students at a grade 2 level is something the students are going to make further inquiries about however I quickly shared how Archimedes discovered this principle, by getting in to a bath tub which immediately elicited a few “Aha” moments so it was good to see some of the students starting to click there. I also shared a short example to leave them with something else to think about which was also taken from the above source,

I asked the students what will happen if you drop  a bowling ball and a beach ball in the water? The students obviously got the answer, the bowling ball will sink, and the beach ball will float! In both cases, the water pushes up against the ball with a force equal to the weight of water it displaced. In the case of the bowling ball, it weighs more than the amount of water it displaced, so it sinks. The beach ball, however, displaces very little water and the air inside it is much lighter than the weight of the water it displaced, so it floats!


Session 5

To continue inquiring in to forces and motion within PE and sports, I decided to set up an activity in stations where students could experience a wide range of sports equipment for a short period of time. I had the stations set up before the students arrived and simply explained that today they would be experimenting with the sports equipment to consider the forces involved in each activity. There were 10 stations in all with basic sports equipment there for each student to try out: Hoola hoops, tennis ball & bat, baseball & bat, rebound nets, football kick, scoops & tennis balls etc. We did a walk and wonder as a class o look at each station, ensuring no-one called out their initial answers before the activity had even begun. As they moved around the stations and participated, I asked them to think about how they got that activity started and how they were able to continue doing that activity, what were the forces involve?

Walking through all of the stations to initially consider the actions/what to do.

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Students participating at some of the different stations.

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Students spent 2 minutes at each station and we had a water break half way through, after 5 stations. During the break we discussed some of our initial thoughts and the students had some great answers, even though not all of them were correct scientific terms: Striking force, rebound force, like a trampoline, curving force, rotating force. A couple of minutes later, we returned to the final 5 stations. Below is a mix video of students at their stations testing out the forces related to sports equipment.


Our final discussion saw the students discuss a few more terms related to the different actions: reflex, spin, swing, speed. Some of the students also noted that many of the forces seemed similar to begin, involving a striking action, like hitting a hockey ball, baseball, tennis racquet/bat and football but because those balls were all so different, different forces were involved. Again, some of these ideas and concepts were seen as something the students could continue to inquire in to for this unit and leading up to their summative assessment task, which is to somehow explain or demonstrate a scientific principle of their choice. Some of them may choose a PE related experiment for example to demonstrate a principle they have covered either in PE or in the classroom.


Session 6

As we are drawing closer to the end of this unit, I wanted the students to get a good understanding of a basic scientific principle related to force and how that could connect to sports. To try and turn this into a game at the same time, I decided to use a game I saw a little while ago on Twitter, Wreck it Ralph. This game is loosely based on the movie and requires teams to have a tower of some sort that that must defend while they also try to attack other teams towers at the same time using balls to throw at the towers. To adapt this game with what I wanted to achieve, I decided to give each team a variety of balls ranging from a small tennis ball size up to a small soccer ball size so that it was really clear which balls would be easier to use for destroying the towers. The photos below show the range of balls in use in this game and some students in action.

Folding mats for team towers, different size balls & students defending and attacking

Set Up Block


Even though it was near impossible to impact upon the towers with the two smallest balls, they were all used throughout the game as the students simply tried to use either the small ball in front of them, or nothing at all. It is clear in the videos below that the few that are seen in the clips have almost no impact on the towers and it is only the two larger balls that can knock them down. So during our first break I asked the students to share their first reflections and other than clearly enjoying the game, the students remarked on how hard it was to try and knock a tower down with  a small ball and how much easier it was to knock a tower down with a large ball. In a previous lesson when the students did the buggy experiment, I quickly introduced the formula F=MA (force=mass x acceleration) and decided to reintroduce it again. I wrote the formula down on a small whiteboard and asked if anyone could identify the ‘M’ in the formula, what was the mass? Someone knew the term and that it related to how much something weighs and we identified the ball and discussed how the heavier ball bas better. At that point, we made a connection: that we can increase the force by increasing the weight of the ball, so I asked what the other way could be, how else can we increase the force? Whilst pointing at the formula, the students identified that if they through it harder/faster then that would also be a way to increase the force to be able to knock the tower down. We decided to get back to the game again for a couple more rounds. The first video below is a good example of the start of the game, where students spent more time protecting their tower and the second video is a mix of various stages of the game with lots of destruction!


Following the second round of games, we quickly reflected again to discuss how far the idea of increasing weight or acceleration could be taken. The students thought they could still throw a heavier ball, like a basketball to make it much easier to destroy a tower but that it couldn’t be too heavy, or else it might be too hard to throw. I then asked for an example and a student thought of a bowling ball, as it would be hard to through through the air, however if bowled, would be hard for the defending team to stop! This was a perfect point to finish the lesson off and tell them about their upcoming PE field trip, to go to the bowling alley!


Session 7 – Bowling

To try and reinforce the previous sessions where we focused on the formula f=ma, I decided to organize a field trip to go bowling. Before beginning, we held a quick discussion on our previous sessions and focused on how the students created force during games such as Monster Ball and Wreck it Ralph. The students were quick to contribute and make connections to the upcoming bowling session by explaining how they could throw/bowl the ball harder or use a heavier ball however they couldn’t use a ball that was too heavy or they would have trouble applying acceleration. Having tried this same experiment last year, I knew the best way for the students to have the most effective session was to get them started by simply getting in to lanes and to get bowling.

Showing some good early form                      Getting some air to pick up the spare

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I wanted the students to enjoy themselves but to also extend our thinking beyond our initial discussion. To do this, I ran a mini experiment with each group at each lane for one frame of their whole round. I wanted to conduct an experiment which hopefully highlighted/demonstrated a difference in force that the students would be able to observe visually. To do this, I used one light weight and one heavy bowling ball for the students to use in one of their turns. We used a ramp to control the speed so that if we looked at our formula (f=ma) we would be increasing the force by increasing the mass. In the first attempt, the students would use the lighter bowling ball and in the second, they would use the heavier one. Whilst it wasn’t perfect science, it was a simple demonstration that the students could understand and hopefully help to gain a deeper understanding.

Just about to roll the pink heavy ball            Discussing the difference in ball weight

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The video below aims to show one of the students first and second attempt, using a lighter and then a heavier ball. It was hard on some occasions as there were some attempts that didn’t strike the centre pin first as well as plenty of gutterballs. However, between the group, the students were able to see a good demonstration of both the light and heavy ball hitting the centre and knocking over pins in different ways.


Some students continued to use the ramp and experiment with balls of different weights while discussing their attempts with their class teacher Mr. David who along with the grade 2 teaching assistants came on the field trip as well. As this unit of inquiry is designed to be transdisciplinary, we have enjoyed discussing their classroom learning in PE as well as vice versa. Shortly, the students will be asked to choose a way that will help them highlight a principle related to forces and motion for their summative assessment task and they could use any of the PE experiments including bowling to help them. The aim is for the students to communicate their understanding of a scientific principle in their preferred way and we will now be focusing on that as we draw closer to the end of this unit. The final discussion focused on how successful the students were in applying different forces to get better results as well as the issue of fatigue as many of them started to tire and couldn’t bowl the ball faster or use a heavier one which led to using the ramp more often. I also told the students that they could use our mini bowling set and different balls at school for their summative assessment task if this was a way they could explain their understanding however, they would need to re-create and write up the experiment themselves, with the help of their teachers of course.

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Session 7 & 8

As the students were well aware of what was required, we only needed a short discussion at the beginning of session 7 before the students started working individually. I invited the students to walk through the sports store room once again to consider all of the equipment that they could use to help them explain principles related to forces and motion with connection to sports and exercise. Some students experimented with different equipment while others discussed their thinking with peers and by the middle of the session, they needed to decide on their sport. As I did a lot of walking around and discussing the task with the students, I didn’t take any photos or videos of this session. I also used my clipboard as I walked around to take notes as to how the students were working and what their choices were.

About 15 minutes later we had a water break and a discussion and the students finalized their choices. I then instructed them to spend the final part of the lesson working on their video & their speech or discussion points in particular. They were to try and get their wording and their story in their head correct first and try to explain this using the equipment at the same time. Once they had composed a basic outline, they could imagine they were being filmed and to try and practice presenting. By the end of the session, the majority of the students felt they were confident enough to film their videos next session.

Session 8 began with the students gathering their equipment and rehearsing for a short time before they began to record with a teacher. We had a variety of choices that would be covered by students: Kicking a football, tug of war, hitting a tennis ball, explaining Wreck it Ralph, hitting a softball, ball-ankle hop and a floatation with kickboards demonstration. The videos below are a few examples of what the students produced