Bell Ringers for Grades 9–12: Friday, November 6, 2026

Answers will vary. Samples:
1. The lab technician tested the samples.
2. The editors made mistakes in the report.
3. Hail damaged the roof of the museum.
4. Passive works here. The reader cares most about the hiker, and the rescuers may be unknown or less important. An active version such as “Rescuers carried the injured hiker down the mountain before sunset” is also fine if the rescuers matter to the story.

Sentence 2 is the best discussion starter: passive voice can hide who is responsible. Ask students who benefits from “Mistakes were made.” Common mistake: calling any past-tense sentence passive. “The dog was barking” uses was but is active, because the dog is doing the action. A quick test: if you can add “by someone” after the verb, the sentence is probably passive. Passive voice isn’t wrong. Lab reports often use it because the procedure matters more than the person. Extension: find one passive sentence in a textbook and decide whether it’s the right choice.

(a) h(0) = 3 feet. (b) t = −b ÷ 2a = −56 ÷ (−32) = 1.75 seconds. h(1.75) = −16(3.0625) + 56(1.75) + 3 = −49 + 98 + 3 = 52 feet. (c) Solve −16t² + 56t + 3 = 0: t = (56 + √(3,136 + 192)) ÷ 32 = (56 + √3,328) ÷ 32 ≈ 3.55 seconds. (d) Solve −16t² + 56t − 37 = 0: t = (56 ± √768) ÷ 32, so t ≈ 0.884 and t ≈ 2.616. The ball is above 40 feet for about 2.616 − 0.884 = 1.73 seconds. (e) It reflects gravity pulling the ball down. It is half of the acceleration, about 32 feet per second squared.

Check on (b): the two times from (d) are the same distance from the peak: (0.884 + 2.616) ÷ 2 = 1.75. ✓ Check on (c): h(3.55) ≈ 0, within rounding. ✓ Common mistake: reporting 1.75 as the hang time. That’s the top of the flight, and the ball takes longer to come down because it started 3 feet up. Note on (d): subtracting roots already rounded to 0.88 and 2.62 gives 1.74, so accept that answer if students show the rounding. Extension: which single number in the equation would you change to model a stronger kick? (The 56, the starting upward speed.)

(a) 10 ÷ 1,000,000,000 × 100 = 0.000001%. (b) 10 × 2ⁿ ≥ 10⁹, so 2ⁿ ≥ 10⁸ and n ≥ log₂(10⁸) ≈ 26.6. That means 27 doublings, or 27 × 0.5 = 13.5 hours. (c) Nearly every cell now has the resistance trait. (d) No. In this model the resistant cells were already there. The drug removed their competition. (e) Answers will vary. Advantage: it may leave helpful bacteria alone. Drawback: the phage must match the specific infection, so it takes testing and may not work on others.

Check on (b): 10 × 2²⁶ = 671,088,640, which is too small. 10 × 2²⁷ = 1,342,177,280, which is enough. ✓ This model is simplified, and the CDC notes that resistance traits can also spread between germs, even to ones that were never exposed to the drug. Keep phage therapy in perspective: the guidelines do not recommend it as a routine treatment, and the report says controlled trials haven’t yet shown how reliably it works. The report also says bacteria can change their susceptibility to phages during an infection, which connects back to (d). Extension: why might doctors combine a phage with an antibiotic rather than use one alone?

Sources: CDC: About Antimicrobial Resistance (selection, spread, gene sharing); ScienceDaily: Scientists Turn Viruses Into Weapons Against Deadly Superbugs (phages, guidelines, cautions); Britannica: Bacteriophage (definition)

(a) 1700, 1800, and 1900 were leap years on the Julian calendar but not the Gregorian one, since none divides evenly by 400. That adds 3 days: 10 + 3 = 13. (b) November 6 − 13 days = October 24, because 2000 was a leap year in both calendars and the gap is still 13. (c) Answers will vary: the same event can have two dates, so readers could mix up the order of events. (d) Answers will vary: religion, tradition, trade, and who holds power. (e) October 24 + 13 = November 6 and October 25 + 13 = November 7, so November 6–7 fits.

The timeline says the Bolsheviks deposed the provisional government and declared that power had passed to the soviets. Keep the focus on the calendar and on how historians handle sources, not on judging the revolution. Common mistake on (a): counting 1600, which was a leap year on both calendars. Check on (e): both Britannica pages agree the Julian dates were October 24–25, so the mismatch is in the conversion. NVCC’s notes also pair October 25 with November 7. ✓ Extension: when will the gap grow to 14 days? (After the Julian leap day in 2100, since 2100 isn’t divisible by 400.)

Sources: Britannica: Why Is It Called the October Revolution? (dates, 13-day gap); Britannica: Russian Revolution Timeline (events, November 7–8); Britannica: Gregorian Calendar (1582, 10 days, leap-year rule); NVCC: Notes on the Russian Calendar (1918 change)

(a) 2,100 ÷ 365.25 ≈ 5.75 years. The observations span about 5 years, so they may not cover a full cycle. (b) λ = c ÷ f. 22 GHz: 3 × 10⁸ ÷ 2.2 × 10¹⁰ ≈ 1.4 cm. 485 GHz: 3 × 10⁸ ÷ 4.85 × 10¹¹ ≈ 0.62 mm. (c) Answers will vary: they look for effects on nearby matter and check whether those effects match a prediction. (d) Answers will vary: evidence can point strongly toward an explanation without finally proving it. (e) Answers will vary: if the stretching stopped tracking the companion’s predicted position, the link would weaken.

Check on (b): frequency went up by about 22 times, and wavelength went down by the same factor (14 mm ÷ 0.62 mm ≈ 22). ✓ Common mistake on (b): forgetting that GHz means 10⁹ Hz. The 2,100-day cycle is a brightness cycle, and the report doesn’t state it as a measured orbital period, so ask students to keep the two ideas separate. The report says the wake is a modeled explanation rather than a direct image. Have students list the hedging words in the report, such as “may,” “believed,” and “suggests.” Extension: why would observing many points along the orbit make this result stronger?

Source: ScienceDaily: A Hidden Star Is Plowing Through Betelgeuse’s Atmosphere, New Evidence Suggests (Siwarha, observations, evidence, cautions, 2,100-day cycle)