##
* *Reflection: Problem-based Approaches
Craft Rocket Challenge #2 - Section 6: Student Activity

Teaching physical science I try to incorperate practical lesson that invoke Newton's Laws and/or computational formulas. Most of my students are familiar with Einstein's famous equation E=MC^{2}, but few know what it actually means. A much more useful formula, and easier to replicate in a classroom, is Newton's Second Law of Motion.

Newton's Second Law states that force (F) is based upon the mass (m) of an object and it's acceleration (a). These three variables are beautifully tied together in the formula F=ma. Most kids can conceptualize the acceleration difference between a motorcycle and a car when they both contain the same engine. A motorcycle has less mass than a car with the same force (engine) propelling it forward, therefor it has greater acceleration.

In this lesson the students will have to manipulate Newton's Second Law to calculate acceleration using the formula a=F/m. The rocket's force (F) is stamped on the side of the rocket, the mass of the rocket is easily measured with a triple-beam balance scale so acceleration is easily computed. If you are still trying to challenge your students you could time the rockets accent with a stopwatch and determine the rockets final altitude with a NASA Altitude Tracker using the formula S=d/t (speed = distance / time) and compare the difference between acceleration and speed.

*Using Newton's 2nd Law*

*Problem-based Approaches: Using Newton's 2nd Law*

# Craft Rocket Challenge #2

Lesson 6 of 11

## Objective: Students will be able to build a large rocket, launch, and determine the altitude the rocket achieves.

This lesson is based on California's Middle School Integrated Model of NGSS.

NGSS Performance Expectation (**PE**): (MS-ETS1-1) Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.

Science and Engineering Practice **SP1 **Asking Questions and Defining Problems. Students are required to build a rocket from household craft material that uses an 'A' Model Rocket Engine and can reach an altitude of 50 meters. These design criteria require that students understand the problem and are sufficiently versed in rocket construction plans and applicable scientific principles. **SP5** Using Mathematics and Computational Thinking. Building a rocket is only half of the lesson, using easily obtainable data students are able to calculate the rocket's acceleration (a=F/m) using the known force (F) of an model rocket engine and weighing the mass (m) of the finished rocket. In addition altitude can be measured using a NASA Altitude Tracker.

Disciplinary Core Ideas (**DCI**): ETS1.A Defining and Delimitating Engineering Problems - The more precisely a design task's criteria and constraints can be defined, the more likely it is that the designed solution will be successful. Specification of constraints includes consideration of scientific principles and other relevant knowledge that are likely to limit possible solutions.

Crosscutting Concepts (**CCC**) Influence of Science, Engineering, and Technology on Society and the Natural World - The uses of technologies and any limitations on their use are driven by individual or societal needs, desires, and values; by the findings of scientific research; and by differences in such factors as climate, natural resources, and economic conditions.

This lesson allows students to build a model rocket from common household materials using a precise set of directions. The criteria for this build is that (a) it must be made from scratch (except engine), (b) reach an altitude of 50 meters, and (c) successfully deploy its flight recovery system (streamer of parachute).

I spend about three days walking the students through the building process step-by-step until they have reached a point where they can work independently. They work in groups of 3-4 students to build the rocket. In their Interactive Science Notebooks that have to create a chart that determines their rocket's altitude using a NASA Altitude Tracker. To calculate altitude the students will have to stand a set distance from the rocket launch and measure the angle from that point. In addition, their chart will include the added complexity of computing the rocket's acceleration (Newton's 2nd Law: acceleration = Force/mass) by looking up the average Newtons of force on the rocket engine (force) and weighing the rocket (mass).

During the construction process I refer back to Newton's 2nd Law (force is dependent on the mass and acceleration of an object). I explain to them that the lighter they can make their rocket, the greater the acceleration will be, which will result in a higher altitude. By explaining this to the students they are less apt to waste supplies (saves budgetary money).

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#### How To Build The Rocket Tube

*60 min*

This rocket tube is considerably larger than the rocket tube built for Craft Rocket Challenge #1. This tube must be strong enough to support a model rocket engine and parachute.

1) Cut a length of 2 inch PVC pipe to 17 inches. You will need one blank per group.

2) Wrap in wax paper. Tuck the ends into the pipe to hold the wax paper in place.

3) Cut a section out of a brown paper bag. The more times the paper can wrap around the PVC pipe the stronger the rocket tube will be.

4) Make a solution of white glue and water. I don't use any specific measurements, just add enough white glue so that the solution has a light syrup consistency.

5) Keep the solution more on the watery side.

6) Dip the brown paper bag into the white glue/ water solution. The wetter the paper bag is, the stronger it will be; while at the same time the longer it will take to dry.

7) Wrap the wet paper bag around the PVC and allow to dry overnight. I teach in the a very arid climate so things dry quickly, you may need to adjust drying times in humid environments. The final edge of the paper bag will curl up as the paper dries. You can see that happening in the photo below. I run a bead of white glue along the edge to seal it. You can also add a few strips of tape to help the edge stay in place as it dries.

8) Carefully remove the PVC from the newly formed rocket dude. You may have to use another length of PVC to ream the old PVC blank from the inside of the rocket tube.

9) You now have a rocket tube suitable for flight. Using ordinary scissors, I have my students trim the edges flat.

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The nose cone will determine the quality of flight your rocket has. Designing a nose cone with a pointy edge versus a rounded edge substantially impacts the altitude of the rocket. I have my students research the difference and design a nose cone of their choosing.

1) I pass out scraps of styrofoam and sandpaper and have my students shape a nose cone. The styrofoam dust makes a mess. We spend about 15-20 minutes cleaning up the styrofoam dust.

2) Cut a small paper clip into a 'U' shape, dip the ends into craft glue and insert into the bottom of the nose cone, allow to dry overnight. Tie a length of rubber band or string to the paper clip loop. This keeps the nose cone from flying away once the rocket ejects its parachute. The other end of the rubber band needs to be glued to the inside of the rocket tube, near the top of the rocket.

As with the nose cone, the fins have a large effect of the rocket's flight. I have my students research rocket fins and design one of their own choosing. I have found that 3 or 4 fins to be the ideal amount.

3) Attach the rocket fins to the rear of the rocket tube. We cut the fins from scrap cardboard and use a hot glue gun to glue them in place.

To keep the rocket stable during lift-off, a guide tube will need to be installed.

4) Cut a small length of plastic straw (1 inch) and glue it parallel to the rocket tube, slightly above the fins.

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A rocket of this size will need a parachute to slow its decent.

1) Use a plastic grocery sack and cut a circle approximately 9 inches in diameter.

2) Poke three holes around the perimeter of the parachute and attach equal lengths of string or yarn.

3) Tie those ends to the rubber band connecting the nose cone to the rocket tube.

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The engine will need to sit in the center of the rocket tube. Spacers will need to be made to hold the rocket engine in place.

1) Use a rocket engine (preferably used). This engine will serve as a mold to build the engine tube. This engine mount design is based on a type 'A' rocket engine, however the design will accommodate any rocket engine diameter, see Step 8.

2) Wrap the rocket engine in wax paper and twist the ends.

3) Cut a length from a brown paper bag that is the length of the rocket engine. The more times you can wrap the paper bag around the rocket engine the stronger the tube will be.

4) As with the rocket tube, dip the brown paper bag into a solution of glue and water. Allow the paper bag tube to dry over night.

5) Open up a large paper clip and fold it as straight as possible. Use wire cutters to trim the paper clip about 1/2" longer than the model rocket engine. Bend the ends of the paper clip over the edges of the rocket engine as seen in the photo below.

6) Poke one bent end of the paper clip into the rocket engine tube. Position the paper clip so that the bottom bent end extends approximately 1/4" aft of the rocket engine tube. Secure the paper clip in place with clear packing tape

.

7) Cut small sections of a 2 inch PVC pipe to serve as guides to build the engine tube spacers. Trace two circles, using the outside edge, onto a piece of scrape cardboard.

8) Mark the center of each circle and use an old rocket engine to trace two inner circles. This particular engine mount design is based on using a type 'A' rocket engine. Any diameter will work as long as you use the same size for this entire build.

9) Cut out the two spacers. I allow my students to cut out the cardboard with razor blades. I review safety procedures and follow a strict safety protocols and check out program for these razor blades.

10) Insert the engine tube spacers over the engine tube. Glue into place using white glue only. Hot glue melts under the extreme temperatures of the firing engine and the engine tube assembly will shoot out the top of the engine. It's a spectacular disaster to watch.

11) Insert the engine tube assembly at the tail of the rocket and again use white glue to secure it in place. Allow the engine tube mount to dry overnight.

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#### Student Activity

*20 min*

For the student activity I place the students in groups of about three to four students (nine total groups). I have found that groups of two can't work fast enough and groups of five or six have to many students not participating. Each group is responsible for building one rocket. Each group also builds a NASA Altitude Tracker with yarn, washer, and a brad. To keep all the groups engaged they have to measure the altitude of all rockets and compute an average. The chart is built in the student's Interactive Science Notebook.

I mark out dashes on the grass at 15 meters and 30 meters from the launch site to aid in the student altitude measurements.

Along with the altitude of the rockets, the students are required to weigh the rocket before launch and record the force of the rocket (found on the engine) to calculate their rocket's acceleration.

Using Newton's 2nd Law (acceleration is based on force and mass) the students weigh their rocket to determine the mass. Commercial model rocket engines post information about each engine's performance. Engines are stamped with designations such as 'A8-3'. The second number (in this case 8) lists the average thrust in Newtons this engine is capable of producing.

By rearranging Newton's 2nd Law (F=ma) to calculate acceleration, you would use the formula a = F/m. By dividing the engines projected force (F) by the rocket's mass (m), the students are able to indirectly determine their rocket's acceleration (a).

Student Work Sample

Each group had to create a chart in their Science Interactive Notebook to record data and calculate results of each group's rocket. The columns where as follows: rocket #, angle of Nasa Altitude Tracker, baseline distance from the altitude tracker to the launch site, altitude of rocket, force of the rocket engine, mass of the rocket, and the rocket's acceleration.

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- UNIT 1: First Week of School
- UNIT 2: States of Matter
- UNIT 3: Periodic Table
- UNIT 4: Atomic Structure
- UNIT 5: Chemical Reactions
- UNIT 6: Forces
- UNIT 7: Density and Buoyancy
- UNIT 8: Motion
- UNIT 9: Solutions
- UNIT 10: Earth, Moon, and Sun
- UNIT 11: Solar System
- UNIT 12: Engineering and Design

- LESSON 1: Prototyping Paper Rockets
- LESSON 2: Mousetrap Racers
- LESSON 3: Hot Air Balloon Challenge
- LESSON 4: Model Rocket Challenge
- LESSON 5: Craft Rocket Challenge #1
- LESSON 6: Craft Rocket Challenge #2
- LESSON 7: Rube Goldberg Challenge
- LESSON 8: Parachute Challenge
- LESSON 9: Balsa Wood Airplane Challenge #1
- LESSON 10: Balsa Wood Airplane Challenge #2
- LESSON 11: Air Rockets