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
Each sentence breaks parallel structure: items in a list don’t share the same grammatical form. Rewrite both so the items match.
- On weekends I like hiking, to swim, and riding my bike.
- The coach told us to stretch, that we should drink water, and getting enough sleep.
Answer and teacher notes
1. On weekends I like hiking, swimming, and riding my bike. (Or: to hike, to swim, and to ride my bike.)
2. The coach told us to stretch, to drink water, and to get enough sleep. (Or: to stretch, drink water, and get enough sleep.)
Quick test: read the sentence’s opening words with each item on its own (“I like hiking,” “I like to swim,” “I like riding”). Each works alone, but mixing -ing forms with “to” forms makes the list feel bumpy. Pick one form and use it for every item. Parallel structure also matters in speeches and essays, where matching rhythm makes ideas easier to remember.
Math
A theater sold 150 tickets for a play and collected $1,350. Adult tickets cost $12 and student tickets cost $7. Write a system of equations and solve it to find how many of each ticket were sold.
Answer and teacher notes
Let a = adult tickets and s = student tickets.
a + s = 150
12a + 7s = 1,350
Substitute s = 150 − a: 12a + 7(150 − a) = 1,350 → 12a + 1,050 − 7a = 1,350 → 5a = 300 → a = 60 adult tickets, so s = 90 student tickets.
Check: 60 + 90 = 150 tickets, and 60 × $12 + 90 × $7 = $720 + $630 = $1,350. Fast estimate for discussion: if all 150 were student tickets, the total would be $1,050; each adult ticket adds $5, and $300 ÷ $5 = 60 adults.
Science
On October 14, 1947, Chuck Yeager flew the Bell X-1 faster than sound at about 662 mph, roughly 40,000 feet up. Yet at sea level on a standard day, sound travels about 761 mph. How could he break the sound barrier while flying slower than 761 mph? Use the speed-of-sound formula a = √(γRT), with γ = 1.4 and R = 287 J/(kg·K), to compare sea-level air at 288 K (15 °C) with high-altitude air at about 217 K (−56.5 °C).
Answer and teacher notes
Sea level: √(1.4 × 287 × 288) ≈ 340 m/s ≈ 761 mph (1 m/s ≈ 2.237 mph).
High altitude: √(1.4 × 287 × 216.65) ≈ 295 m/s ≈ 660 mph.
The speed of sound depends on air temperature, not on altitude directly. In the cold air near 40,000 feet, sound is slower, so 662 mph was just over the local speed of sound (662 ÷ 660 ≈ Mach 1.00). Note that speed scales with the square root of temperature: the absolute temperature drops about 25 percent, but the speed of sound drops only about 13 percent. The actual temperature that day may have differed from these standard-atmosphere values.
Sources: Britannica: Chuck Yeager; NASA Glenn Research Center: Speed of Sound
Social Studies
The Battle of Hastings, fought on October 14, 1066, made the Normans rulers of England. Much of what people picture about it comes from the Bayeux Tapestry, an embroidered strip of linen about 230 feet long with more than 70 scenes. It may have been commissioned by Odo, bishop of Bayeux, who was William the Conqueror’s half brother. As a historian, what two questions would you ask before trusting the tapestry as evidence? How might its origin shape the story it tells?
Answer and teacher notes
Answers will vary. Strong questions: Who made it and who paid for it? When was it made, and how long after the events? Who was the intended audience? What does it leave out? Does it agree with written accounts from both sides?
If a close relative of the winner sponsored it, it likely presents the Norman conquest as justified and may give Odo a flattering role (Britannica notes he is prominent in the later scenes). That doesn’t make it useless: it is still excellent evidence for clothing, weapons, ships, and how the Normans wanted the story told. The exact date is unknown, but it is generally dated no later than about 1092. The tapestry is on display at the British Museum in London through July 2027, its first time in England in about 900 years.
Sources: Britannica: Bayeux Tapestry; Britannica: Battle of Hastings; NPR: The Bayeux Tapestry returns to England
Current Events
A University of Vienna team reported this week in Nature Communications that, hundreds of millions of years ago, the DNA of octopuses, squid, and cuttlefish was reorganized so that once-separate regions of their chromosomes came into close contact. Many of the new, changeable DNA loops sit near genes tied to the nervous system. The researchers propose this may help explain how these animals became so intelligent, but say the study does not prove it. (a) Why can’t they yet claim the DNA change caused the intelligence? (b) Describe one kind of evidence that would make the claim stronger.
Answer and teacher notes
(a) The study shows a pattern: DNA structure changes that sit near nervous-system genes. A pattern or correlation is not the same as cause. Other changes could explain the intelligence, and scientists can’t rerun evolution to test it.
(b) Answers will vary. Strong ideas: show that disrupting specific loops changes how those nervous-system genes switch on; compare more species, including cephalopod relatives with simpler nervous systems; or link the loops to differences in brain development. Push students to name what result would weaken the idea, too. The authors call the process “regulatory entanglement.”
Source: ScienceDaily: Scientists Find a Surprising Genetic Twist Behind Octopus Intelligence (University of Vienna; Nature Communications, 2026)