ETS1-2., 3-5-ETS1-3. MS-ETS1-1., MS-ETS1-2., MS-ETS1-3., MS-ETS1-4. HS-ETS1-2., HS-ETS ETS1-1., 3-5-ETS1-2., 3-5-ETS

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1 Level: Elementary, Middle, and High School Type of Contest: Team Composition of Team: 2 4 students per team Number of Teams: One entry per school Next Generation Science Standards: Overview ETS1-2., 3-5-ETS1-3. MS-ETS1-1., MS-ETS1-2., MS-ETS1-3., MS-ETS1-4. HS-ETS1-2., HS-ETS ETS1-1., 3-5-ETS1-2., 3-5-ETS The objective of this challenge is to engage students in the engineering and design process through the construction of a wood bridge, which will be assessed for its strength-toweight ratio (efficiency). Constructed bridges are intended to be simplified versions of realworld bridges, which are designed to accept a load in virtually any position and support that load without failure/collapse. In this challenge, only one loading position (the center position) will be tested. NOTE All entries must be checked in upon arrival at. General Rules The competition is judged based on scores for each of the following general rules The Scoring Sheet provides details on the scoring of each of the competition judging components with the following essential rules: 1. Prior Construction: All bridges must be built before the day of the competition. 2. Registration: All bridges must be registered the morning of the competition and are to be turned over to the lead judge immediately after registration. 3. No Modifications: Once the bridge is registered, no repairs or modifications will be allowed. 1 NGSS Lead States (2013). Next Generation Science Standards: For States, By States. Washington, DC: The National Academies Press: 1

2 Wood Materials The overall design and construction of the bridge will be judged on the following characteristics: 1. Wood Type The bridges must only be constructed from the assigned type of wood for the team s grade level (Balsawood = Elementary School) (Basswood = Middle and High School) and any commonly available adhesive. NOTE Please use discretion when selecting adhesives, as some adhesives may contain potentially hazardous materials. 2. Size and Shape Various wood member sizes are allowed for construction. However, all pieces must have originated as square beam/stick style shapes (no circles). See Figure 1. Figure 1. Original Square Beam/Stick Shape 3. Cutting and Sanding The wood may be notched, cut, or sanded in any manner but must still be identifiable as the original wood. 4. Materials Restrictions No other materials (apart from the wood and selected adhesive) may be used. The bridge may not be stained, painted, or coated in any fashion with any foreign substance. 2

3 Wood Competition Measurement Requirements Table 1 lists the required measurements of the bridge components for elementary, middle, and high school entries. Table 1. Competition Measurements Competition Measurements Elementary Middle High Distance the bridge must Span (S) 28 cm 30 cm 30 cm Maximum Length of the bridge (L) 38 cm 36 cm 34 cm Maximum Height of the bridge (H) 14 cm 20 cm 15 cm Maximum Width of the bridge (W) 10 cm 8 cm 7 cm The bridge mass must be no greater than 30 g 25 g 20 g Construction Parameters The following construction parameters will be used in judging entries: 1. The wood may be notched, cut, and/or sanded. 2. Members of the bridge may be laminated. 3. s are not to be painted or decorated in any way, but they may have the team's name and grade written on it (sparingly) with a pen/pencil for identification purposes. 4. No portion of the bridge may extend or project below the top of the support surfaces. 3

4 Wood Loading Parameters The following loading parameters will be considered in judging entries: 1. s will be set for testing while being loaded vertically. The loading plate will rest on the center top of the bridge while weight will be added by competitors to the container loaded below the bridge. 2. Competitors may not hold the container up with their hands and may only make brief physical contact with the container while loading. 3. Grade level will determine which loading plate will be applied for testing: Elementary: The load will be applied by the means of an 8.5-cm square plate that is 1.5 cm thick. Middle and High School: The load will be applied by means of a 50-mm square plate that is 6.35 mm thick. 4. For all grade levels a 3/8-in. bolt will be attached from below the bridge to the center of the loading plate. The bridge must allow space to receive the bolt for loading/testing. 5. The loading plate must be horizontal when it rests on top of the bridge. 6. When the bridge is set and the judge is ready, team member(s) (two maximum for this task) will begin loading from below until bridge failure or a load mass of 15 kg or (15,000 g) has been reached. Failure is defined as a deflection beyond 3 cm (as measured at the center line) of the bridge. 7. If a bridge falls over, the bridge will have failed regardless of deflection. 8. s failing above 15 kg will be considered to have held 15 kg for the efficiency calculation. 9. The recorded mass held will be the last mass held while the bridge was still standing. The mass at which the bridge collapsed will not be recorded as the mass held. 10. Eye protection must be worn while loading/ testing the bridge. Teams are expected to bring their own pair of safety glasses for each participating team member at competition. 11. The team that remains competitive by following all stated rules and earns the highest calculated efficiency score (barring any needed tie-breakers) will be declared the winner. Efficiency = Load supported in grams/mass of bridge in grams 4

5 Wood Qualification 1. All construction and material requirements will be checked before testing by the judges. s that fail to meet these specifications at the conclusion of the allowable time for check-in (set by competition director) will be disqualified. s disqualified prior to the start of the contest may be tested as exhibition bridges at the discretion of the judges. 2. If, during testing, a condition becomes apparent (e.g., use of ineligible materials, inability to support the loading plate) that is a violation or prevents a bridge from being tested as described above, that bridge shall be disqualified. If the disqualified bridge can accommodate loading, it may still be tested as an exhibition bridge as stated above. Grounds for Disqualification The following are grounds for disqualification: 1. Failure to comply with any of the previously mentioned competition rules is grounds for disqualification. 2. No bridge modifications will be allowed after the bridge has been submitted for testing. This includes removing members, adding members, or modifying the length, height, or width of the bridge. Each team should inspect their bridge according to construction rules before submission. 3. Use of a wood grain other than what is listed for your grade level. 4. Failure to use safety glasses/goggles NOTES Disqualified teams will receive the lowest possible rank plus an additional rank down (+2). Example: A disqualified team in a competition of 10 teams would receive the rank of 12. 5

6 Wood Scoring (Highest Efficiency Wins) The following is an example of bridge scoring: Parameter Team A Team B Maximum Load (g) 7,000 4,000 Mass (g) Efficiency E = (g/g) 7,000 g/13 g = g/10 g = Efficiency Score = Mass held by bridge/mass of bridge Winner = Team A (Highest Efficiency = ) s If a tie occurs between qualified bridges, the following will be used to break ties: 1. Lightest Mass 2. Shortest Length (if needed) 3. Tallest Height (if needed) The Scoring Sheet lists the length, height, amount of weight held, mass of the bridge, bridge efficiency, team qualifications and rankings of teams. NOTE All entries must be checked in upon arrival at. SAFETY Appropriate safety measures are to be used at all times. ALL DECISIONS MADE BY JUDGES ARE FINAL All MESA teams are encouraged to enter the Maryland Engineering Challenges. For more information, visit the Engineering Challenges page on the Baltimore Museum of Industry website: 6

7 Scoring Sheet Judge(s): _ School Length of #2 Height of #3 Amount Held (g) Mass of (g) #1 Efficiency = E (g) Held / Mass Was the Team Disqualified? (Yes/No) Event Rank (1, 2, 3, etc.) Disqualified = last possible rank

8 Scoring Sheet Judge(s): _ School Length of #2 Height of #3 Amount Held (g) Mass of (g) #1 Efficiency = E (g) Held / Mass Was the Team Disqualified? (Yes/No) Event Rank (1, 2, 3, etc.) Disqualified = last possible rank