2025 MIT Invitational

[xpiyr]

Team list has been posted

[xpiyr]

Event Supervisor Review: Tower

Setup: Structures were tested using automatic loading setups. Ultra-fine, low-dust sand was used as the free-flowing material. The Test Base was a sheet of birch plywood with laser-etched markings for the bonus circle and four quadrants. Engraving settings were adjusted to ensure a fine, superficial engraving, with the bonus circle intentionally designed with a 28.9 cm diameter to account for kerf width. Dimensions were verified after manufacture. The Loading Assembly consisted of a Loading Block made of solid wood, an eyebolt with length of approximately 3 inches, two S-hooks measuring approximately 1/4 inch by 2 inches, and a double-looped chain. Two testing setups were available with equivalent components (eyebolts, S-hooks, chain lengths, etc.), though some teams preferred one setup, which they observed to allow slightly faster loading.

Tiers: Of the 72 registered teams, 68 presented devices, with 63 (93%) in Tier 1, 4 (6%) in Tier 2, and 1 (1%) in Tier 3.

Scores: The winning score was 4,434.59, with a structure mass of 4.51 grams that successfully held all 15,000 grams. Tower masses ranged from 4.51 grams to over 400 grams. Twenty-nine teams supported the full 15,000 grams, of which 25 qualified for the bonus. Many teams attempted the bonus but did not earn it, as their structures broke before reaching 15,000 grams. Only a few structures failed within 500 grams short of the full load.

Comments/Observations:

1. Variation in Loading Assembly. Every year, a handful of teams struggle with a competition-day Loading Assembly that differs from the one they practiced with and designed their structure around. Remember that the rules allow a range of lengths for the eyebolt, so your structure must accommodate eyebolts of any length within that range. A slightly greater challenge—especially for Tower compared to other structure events—is that the S-hook specified in the rules does not have a fixed dimension. Therefore, teams should not design their Tower to fit precisely around an S-hook of a particular size.
   
   This was the most common challenge I observed during setup, where teams struggled to fit the S-hook through their structure without damaging the surrounding framework. Fortunately, no teams were completely unable to accommodate the Loading Assembly, but those that encountered this difficulty tended to spend significant time on setup.
   
   
2. Building precision. As with every year, a few teams built right to the dimensional specifications in the rules, which is impressive but risky when practicing on a tournament-day setup. Two key specifications where this was relevant this year were the Loading Block height and the bonus circle.
   
   Firstly, measuring accuracy varies, and it is difficult to dispute a difference of a couple millimeters between rulers. If the Event Supervisor's ruler measures slightly longer than yours, your structure built to 51.0 cm may not fall under 50.0 cm, but if you built exactly to 50.0 cm, you now have a Construction Violation.
   
   Secondly, measuring the Loading Block height is challenging because it is a vertical measurement that cannot be taken by simply holding a ruler against the Loading Block, especially with common Tower designs that are angled. Furthermore, an unlevel Loading Block relative to the Test Base can introduce and complicate parallax error correction. To improve accuracy, we mounted two bubble levels with a combination square to a meterstick at 49.9 cm, allowing for a direct, up-close measurement of Loading Block height. Even with this method, a few teams were still too close to the minimum dimension.
   
   Thirdly, even if your Loading Block measures exactly 50.0 cm prior to loading, once your Tower is loaded, it will begin to settle and arguably no longer meets that specification.
   
   Finally, for the bonus circle, drawing a precise 29 cm diameter circle is difficult without a large compass or stencil. Even with a precisely manufactured circle slightly under 29 cm in diameter, off by nearly 1 mm, a few teams' Towers barely missed touching the bonus circle. To avoid potential Construction Violations, teams should prepare for circles that may not be perfectly circular and could be marked with thick lines.
   
   My recommendations are to build your Tower to support a Loading Block at least 50.5 cm, even 51.0 cm, above the Test Base. For the bonus circle, design for a 29.5 cm diameter or larger. The structural and mass differences in building slightly larger are minimal compared to the risk of a Construction Violation, which could significantly impact your ranking.
   
   
3. Eye protection. Eye protection is required for this event and must be properly fitted. If you wear prescription glasses, wearing safety glasses over them that project outward from your face without proper seating on your nose bridge does not meet the requirements. This setup does not provide adequate protection and does not satisfy the event’s safety standards. Additionally, per guidelines, teams must be able to display the Z87+ marking.

In summary: be prepared for eyebolts and S-hooks that are smaller or larger than your usual size, do not build too close to the specifications for Loading Block height and the circle bonus, and present proper eye protection that is compatible with prescription glasses if you wear them.

tower_2025_c_mit_scores.png

[Unome]

I don't have nearly as much to say as bernard but,

Event Supervisor Review: Geologic Mapping
I wrote Sections D, E, and F, so I'll cover those:

Section D: Relatively straightforward section for this level of competition, wrapping together several fundamental concepts in one part, and as expected teams generally did well on this. As the per-section scores graph shows, the score distribution was practically a straight line from 0% to 100%.
Section E: This section was in essence a one step removed three-point problem, with some associated interpretive questions. As is frequently the case with math, a lot of teams didn't get many points (though I always try to break up problems into multiple parts and guide teams through the steps, which usually works out alright), while the higher-scoring teams in this section were often doing well.
Section F: I had a bit of trouble finding higher-resolution maps of this region (the Arkansas River Valley, located between the Ozarks and Ouachitas), but I was largely able to work around that and ask questions that weren't so relevant on reading tiny details.

The score distribution is included in the test release folder - it's pretty much the same shape as last year, but with higher percentages. Overall, teams did a bit better than I expected, but definitely not to the point of causing any trouble.