45-60 minutes

Students and their teachers are introduced to basic physics concepts and the idea of variables through use of Mattel™ Hot Wheels tracks and steel balls. Students will use the design process to explore force and motion. This series of lessons allows students and teachers to work through the design process in order to investigate physical science and experimental design concepts.  It highlights the design process as a tool allowing students to approach issues in a meaningful and productive way. This unit follows a learning cycle of Focus - Explore - Reflect - Apply.  The cycle is followed throughout the entire unit as well as within individual lessons.  It allows students to observe phenomena during their investigations which will lead them to ask questions and design systems in which to explore answers to their questions - and on to further questions.

Science Standard 10. Level II. Understands forces and motion 2. Knows that the Earth’s gravity pulls any object toward it without touching it 5. Knows that when a force is applied to an object, the object either speeds up, slows down, or goes in a different direction 6. Knows the relationship between the strength of a force and its effect on an object (e.g., the greater the force, the greater the change in motion; the more massive the object, the smaller the effect of a given force) Standard 11.  Level II. Understands the nature of scientific knowledge 2.  Knows that good scientific explanations are based on evidence (observations) and scientific knowledge 4.  Knows that scientists review and ask questions about the results of other scientists’ work Standard 12.  Levels Pre-K and II. Understands the nature of scientific inquiry 1.  Knows that scientific investigations involve asking and answering a question and comparing the answer to what scientists already know about the world 2.  Knows that scientists use different kinds of investigations (e.g., naturalist observation of things or events, data collection, controlled experiments), depending on the questions they are trying to answer 3.  Plans and conducts simple investigations (e.g., formulates a testable question, plans a fair test, makes systematic observations, develops logical conclusions) 5.  Knows that scientists explanations about what happens in the world come partly from what they observe (evidence), partly from how they interpret (inference) their observations

This lesson works as a formative assessment to check student understanding of concepts learned throughout the unit.  Students work in teams using concepts explored in previous lessons to design a racetrack with a clear goal.  They challenge classmates to timed races using specific materials. Students will: •    demonstrate understanding of how variables affect the outcome of the way in which a projectile travels through a track •    recognize the design process as a creative challenge employing the skills of observation, research (data collection), problem solving, construction, revision and sharing results •    use the design process as they set up a track in order to achieve a specified outcome The variables that students will add at this time are: loop, hill, and jump  

Each group of students will need:

• track pieces (8 short plus 1 long)
• connectors (5)
• c-clamp or masking tape
• jump (launch and catch pieces – 2 per team)
• one loop piece
• meter stick
• masking tape
• can (to be used as target)
• foam blocks to make hills
• small steel balls

Individual Students will need:

• Racing Challenge Data Sheet

Display for Whole Class:

• Design Process Poster

1. Teacher Presentation: Put the students into teams and give them the following challenge: Design a track that will carry the small steel ball as fast as possible.  Use what you’ve learned so far while doing the previous Hot Wheels™ investigations.  Your track must use all nine track pieces and include the following components: •    Release – from the back of a chair •    One loop (constructed from a loop piece and the long piece of track) •    At least one jump 20 cm or longer •    At least one hill at least two foam blocks high 2. Once the teams have their fastest tracks they should challenge another team to a race. 3. Students should record the results of each race and draw the two track designs on the Challenge worksheet. (Note:  Allow a minimum of two hours to design, build, test tracks and race with other teams.) 4. Class Discussion/ Wrap up and shared learning: Have teams compare and discuss the results of their races.   Focus discussion on how the variables affected each design.  Suggested prompts for small group discussions:

• What did you notice about each track?
• Why did one track work faster than another?
• Where did the object traveling on the track speed up or slow down and why do you think that happened?
• How could either of the tracks be improved?

5. If using a design journal have individuals record their team track design and write why they think it was a good design and what they have noticed that would help them make improvements on their design in the future. 6. Share highlights of the small group discussions with the whole class by recording new insights on chart paper to be posted by the Design Process Poster.        

Ask students to share what they think are the important ideas from the past design lessons (The Big Ideas).   Have them discuss with partners and then have the groups share with the whole class.   This will give you a chance to assess their understanding of the objective and to clarify or restate ideas that are not brought forward by the students. Prompts for small group discussion from lesson "wrap-up" portion could be used to individually assess students.    

Extension:  The Gravity Game This extension encourages creativity.  Teams invent ways to turn their track into a game that scores points.  Teams are given the Gravity Game worksheet with a checklist of criteria they must include in their track design.  Allow a minimum of two hours for students to design, build, and test the track.