Step 2: Day 2... Building and Newton #2 and #3
Tools and Materials:
-Hot glue and Hot Glue guns (not required...see below)
-2 Liter bottles
-scissors, x-actos, mat knifes...etc
-Material for batting
-2 skateboards (if you can find them...)
The kids are ready to build but first you can do a fun demo. The first law i teach about is Newtons 2nd Law...
"The more massive an object is... the more force it takes to accelerate it" or you could say...
"Heavy stuff takes more force to move"
I like to demonstrate this by pulling up the smallest kid in the class. I pull out 2 skateboards.. facing each other and about 2 feet apart. I put the student on one skateboard and i stand on the other. I'm not a big guy but usually the size discrepancy is pretty obvious. I longboard as a hobby but i act like I've never stood on one. the kids like that... I ask the student to hold out both hands in front than i do the same. I ask the class what would happen if we pushed our hands together really hard. Of course the kids know what happens so i gently push on the hands of the student. Its amazing how far a kid will roll. I won't move more than a couple of inches.
I get the kids to notice 2 things.
-The person with less mass moved further
-The person with more mass actually DID move a bit.
Newtons 2nd law relates to the idea that more massive objects will take more energy to accelerate, or move. The person with less mass moved more because it takes less energy to move them.
The other part of the demo is that the more massive person still moved... This is explained by Newtons 3rd law which says:
"To every action there is an equal and opposite reaction" or you could say...
"if you push something it will push back"
The kids notice that i move as well. You could explain the idea that every time objects move each other BOTH have the same force being pushed on them. More massive objects don't MOVE as much but they still have the same energy exerted on them. This is also a good explanation for why we add water to the bottle. The water being pushed out from the bottle has more mass than just air so it pushes against the bottle harder which forces the bottle up with more force. You can tie this into Newtons 2nd law as well if the kids are still engaged at this point.
Now you can start BUILDING STUFF
Pull out the drawings, gather the materials and demonstrate a couple of skills...
-Stacking bottles for height.
Show how to cut a bottle safely with a blade. keep the cap on when starting... makes it easier. I cut a bottle open about 4 inches up from the bottom than show how they can stack. Its up to you if you want the kids to use blades. It worries me so i ask the kids to use scissors AFTER i start the cut for them.
I give out a meter at a time. Kids will use a whole roll if left to it. I demonstrate how much tougher and more accurate it is to use 4" strips of tape placed lengthwise. i do one side, line up for symmetry than tape the other.
-Using drawings as patterns
I ask the kids to use the drawings as a pattern to cut out the fins and other parts... I find a scroll saw works great on cardboard and coroplast.
-Attaching stuff to the bottles
Use sandpaper to scuff up wherever they want to attach things. Hot glue works well but i find that it is used WAY too much and kids burn themselves. I find tape works well. The fins can also be taped on with care.
Remind the kids about a couple of things...They forget that the egg has to go in and out easily. I cut a hatch in the top bottle. Remind the students that they MUST NOT puncture the BOOSTER BOTTLE at all. Usually one team will forget this. You will also get at least one team that will forget that the booster bottle goes TOP DOWN and they will tape the fins on upside down. Make sure they understand SYMMETRY and that the rockets work really well if they are about 2 times the length of a bottle.