Five warm-ups for grades 9–12. Each takes three to five minutes. Answers and teacher notes are in the collapsed box under each prompt.
ELA
Words can share a denotation (dictionary meaning) but carry different connotations (feelings). Rank each set from most negative to most positive. Then write one sentence about a friend using a word from any set, chosen to show how you feel about them.
- cheap, frugal, thrifty
- nosy, curious, inquisitive
- arrogant, confident, self-assured
Answer and teacher notes
Typical rankings, negative to positive: 1. cheap → frugal → thrifty. 2. nosy → curious → inquisitive. 3. arrogant → self-assured → confident. The middle and top words are close, so accept any order students can defend; the clearly negative word (cheap, nosy, arrogant) should land first.
Discussion: “My uncle is cheap” and “My uncle is thrifty” describe the same behavior but reveal opposite attitudes. Writers choose connotations to steer readers, which is why noticing word choice is a key skill for reading arguments and ads. Have two students read their sentences aloud and let the class guess the writer’s attitude.
Math
A lab culture starts with 500 bacteria and doubles every 20 minutes. (a) Write a function N(t) for the population after t minutes. (b) How many bacteria are there after 2 hours? (c) After how many whole doublings does the population first pass 1,000,000, and how many minutes is that? (d) Why can’t a real population keep doubling forever?
Answer and teacher notes
(a) N(t) = 500 · 2t/20
(b) 2 hours = 120 minutes = 120 ÷ 20 = 6 doublings. 500 × 26 = 500 × 64 = 32,000.
(c) We need 2n > 1,000,000 ÷ 500 = 2,000. Since 210 = 1,024 and 211 = 2,048, it takes 11 doublings = 220 minutes (3 hours 40 minutes). Check: 500 × 2,048 = 1,024,000. Using logarithms, the exact crossing is t = 20 · log2(2,000) ≈ 219.3 minutes.
(d) Food, space, and oxygen run out, and waste builds up, so growth slows and levels off. That leveled-off pattern is called logistic growth. Common mistake in (b): writing 500 × 2 × 6 = 6,000, which treats doubling as adding instead of multiplying.
Science
On October 16, 1846, at Massachusetts General Hospital in Boston, dentist William Morton gave a patient ether so a surgeon could remove a tumor from his neck. It was the first successful public demonstration of ether as a surgical anesthetic. Diethyl ether has the formula C4H10O. Using C = 12.011, H = 1.008, and O = 15.999 g/mol: (a) find its molar mass, (b) find the percent of its mass that is carbon, and (c) find how many moles are in 25.0 g.
Answer and teacher notes
(a) C: 4 × 12.011 = 48.044. H: 10 × 1.008 = 10.080. O: 1 × 15.999 = 15.999. Total = 74.123 g/mol (about 74.12).
(b) 48.044 ÷ 74.123 × 100 ≈ 64.82% carbon. (Hydrogen ≈ 13.60%, oxygen ≈ 21.58%; the three add to 100%.)
(c) 25.0 g ÷ 74.123 g/mol ≈ 0.337 mol.
Today marks 2026 − 1846 = 180 years since what Boston still calls “Ether Day.” The operating room, later nicknamed the Ether Dome, still stands. Safety note: ether is extremely flammable, one reason hospitals later replaced it with other anesthetics. Discussion: why did a public demonstration matter so much for getting doctors to adopt a new method?
Sources: Britannica: William Thomas Green Morton; Linda Hall Library: Ether Dome
Social Studies
For centuries, England’s treasury, the Exchequer, recorded debts on wooden tally sticks. When a debt was issued, the stick was split in two, and the halves were later fitted back together to confirm payment. The system had not been used since 1826. On October 16, 1834, workers burned two cartloads of old tally sticks in the furnaces under the House of Lords, and the fire spread through most of the Palace of Westminster. (a) Why would a stick split in two be hard to cheat with? (b) Name a modern record-keeping method that works on a similar idea. (c) What lesson about getting rid of old records or systems does this story suggest?
Answer and teacher notes
(a) Each party kept one half. A split piece of wood has a unique grain and break, so only the two original halves fit perfectly; a forged or altered half would not match.
(b) Answers will vary: a receipt where both buyer and seller keep a copy, a check and its stub, ticket stubs, or digital transaction records stored by both a bank and its customer. The shared idea is that two parties each hold matching proof. (c) Answers will vary: plan disposal carefully, follow safety warnings, and don’t assume an outdated system is harmless. Visitors noticed heat and smoke that afternoon, but the warnings were ignored. Westminster Hall survived, and the rest of the palace was rebuilt into the building seen today.
Sources: UK Parliament: The fire of 1834; History of Parliament: Burning the House Down: The Fire of 1834
Current Events
Today is World Food Day. Blast disease, caused by the fungus Magnaporthe oryzae, destroys enough rice each year to feed about 60 million people and also threatens wheat and barley. A study published October 15, 2026, in Science Advances by the John Innes Centre (UK) and Kobe University (Japan) reports that scientists engineered a plant immune receptor to recognize two different fungal molecules instead of one. So far it has been tested only in individual wheat cells. (a) Why can’t the team yet claim it protects wheat crops? (b) Why might a receptor that detects two fungal molecules be harder for the fungus to escape than one that detects a single molecule?
Answer and teacher notes
(a) Single cells in a lab are not whole plants growing in real conditions. The receptor must still work in full plants, first in greenhouses (the team’s stated next step) and later in fields, without harming growth or yield. A promising early result is not the same as a proven solution.
(b) Pathogens evolve. If a plant detects only one fungal molecule, a mutation that changes or drops that molecule lets the fungus slip past. Detecting two means the fungus would need changes in both, which is less likely. Natural receptors with this kind of dual recognition are unusual, which is why the result is notable. Extension: why would scientists also study combining different receptor types for layered protection?
Source: ScienceDaily: A Fungus Is Threatening the World’s Food Supply. Scientists Just Found a New Defense (John Innes Centre; Science Advances, 2026)
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