At first, I followed the tutorial video and used the example’s ideas. Then in the second class, when I finished the base structure and the arm, I started to build it myself. As you can see, my final product is very different from the tutorial, I have some similar parts, but many parts were changed. Because when I was building, some parts were too detailed, so I changed them and added my designs. My toy meets the design goals because it generates elastic potential energy to kinetic energy. You can see, when people press the swing arm down and shoot, it works smoothly. When people press the catapult arm, the rubber bands will be stretched, elastic potential energy will be created, and when people release the arm, the rubber band will pull back (kinetic energy will happen).

I am proud that I built a catapult that actually worked, and the design and sketches are almost the same as my final product. A challenge I faced was when I tried to cut the popsicle sticks into small pieces, it’s hard to cut using the saw, and when you cut it through, it will break into small pieces. However, I over come the challenge and found that using the most regular scissors would work the best. Another challenge before I start to build the actual catapult is that I struggle with what I should change from the original tutorial. So, I followed the tutorial in the beginning, and after gaining some experience and ideas, I started adding in my designs and pieces.

A strength in my entire project is that I used other classmates’ and teachers’ feedback to improve. With the changes in my catapult, it worked better than before. Something I can do better next project is, when I define and plan, I should look at more design examples and draw more catapult designs. I should also label better in my design sketch to be more precise and accurate. Another thing is I should calculate how much popsicle sticks will I use again, because the materials used in the final product is kind of different from the original plan.  Since there are no large size popsicle sticks, I changed it all to normal size sticks, so, the amount of popsicle sticks changed. At the end of the class, I made some paper balls to be bullets and a small basket to be the target to make it more fun for the kids. To sum up, the process and the plan are successful, and my toy design works well.

I met the different standards because I clearly defined all details of the design and explained who are the targeted audience. I also asked different people for feedbacks and improved my catapult using the feedbacks. My design clearly explained the energy transfer (potential to kinetic), and kids can learn when they play with it. I met my goals of the define and plan process, where the catapult can move smoothly and how it can shoot 1 meter forward, which my final catapult did much better (it can shoot 2 meters).

My final product:

(back of my catapult)

A demo of my catapult:

 

Reflect on your prototype. What were some strengths? What needs refinement

A strength is that the catapult can shoot really far away, and when the arm is moving, the sticks won’t fall apart. However, the base of the catapult is too light, so when people shoot and move the swing arm, the base structure will move forward and wobble. I plan to add more weight by using more popsicle sticks at the front and back of the catapult.

Feedbacks from classmates and teachers:

Sharon- Add more weight on both front and back side, so when you shoot the balls the base structure will be stable.

Jason- Not stable when you play with it, the catapult will fall forward.

Ms. Karen- Add something that can pull the catapult back rather than using hands to press the catapult’s arm (ex. add a string or a rubber band at the back of the swing arm).

Josiah- Very well built, seems sturdy and stable, maybe add some colors.

Catapult before changes:

• The base was kind of light because I did not use a lot of sticks.
• The back of the catapult is lighter than the front, so when it shoot it will fall forward.

Catapult after changes and improvements:

• I added more layers of popsicle sticks at the back of the catapult and the middle of the structure, as you can see in the second and third image.
• I also added a rubber band around the catapult’s arm, so when people press the catapult down, they don’t have to press the arm, they can just pull the rubber band.
• I also added a hook at the back of the catapult, to add more weight to the body frame, and to make the rubber band stay. Because without the hook, the long rubber band at the back is easy to fall or loosen.

I looked at many designs of catapult for inspiration, and decided to use one of them as my tutorial. I’ll follow the steps and change the details while I am building it. The materials I will use are popsicle sticks, water bottle caps, rubber band, and steel wire. I will connect the different parts of the catapult by using hot glue. I plan to use two classes to finish the catapult, and use one class to finalize and add some final bits and details.  There are not a lot of skill needed, I just need to cut the popsicle sticks and glue it together. To be successful, I have to follow the steps and be accurate when I stick the materials together. Before I put all the things together, I have to carefully watch the tutorial and fully understand what I have to do. Because any wrong measurement or sticking at the wrong place will affect the final prototype, and the swing arm might not work. I believe, if I follow the tutorial on how to make the base and arm connect, then it will work out fine.  If I have time and left materials, I will make a mini basket/ target for the catapult. Since the client of this toy is around 10 years old, while they learn energy transformation, the design should also be engaging and fun. Also, my goal is to let the balls shoot high and one meter away.

My catapult design + sketch: