ILTS Science: Chemistry (240) case studies
ILTS Science: Chemistry (240) · Put your knowledge to work in context.
The ILTS Science: Chemistry (240) test is one of the subject-matter exams in the Illinois Licensure Testing System, used by the Illinois State Board of Education as part of the requirement for a chemistry teaching endorsement. It is aimed at candidates who already hold or are completing a teacher-preparation program and want to teach chemistry, often alongside another science area, in Illinois middle or high schools. The ILTS Science: Chemistry (240) case studies are 5 cases and about 3,230 words.
1The Fertilizer Fair: A 40% Claim Built on Confounded Trays
At a district science fair, a high school junior presents a project titled 'GrowBoost Increases Radish Growth by 40%.' She mixed three nutrient concentrations: 0 mL, 5 mL, and 10 mL of GrowBoost per liter of water. For each concentration she filled one tray with four radish seedlings, watered all trays with 50 mL every other day, and measured stem height after 21 days.
676 words, about 3 min2The 118% Copper Yield
In Chemistry II, students prepare 250.0 mL of 0.100 M copper(II) sulfate solution from CuSO4·5H2O (molar mass 249.68 g/mol) and then react 25.00 mL aliquots with excess iron nails to recover copper metal. The pre-lab calculation gives 6.24 g of the hydrate.
654 words, about 3 min3The Sealed Tube That Would Not Follow the Rule
During a unit on equilibrium, a teacher prepares three sealed glass tubes containing an NO2/N2O4 mixture. The tube in ice water is pale brown; the room-temperature tube is medium brown; the tube in hot water is dark brown.
635 words, about 3 min4The Pink Endpoint That Came Too Soon
Students standardize a sodium hydroxide solution with potassium hydrogen phthalate and obtain 0.0987 M NaOH. They then titrate 25.00 mL of an unknown acetic acid solution with phenolphthalein.
643 words, about 3 min5The Reaction-Rate Lab That Needs a Safety Plan
A first-year chemistry teacher plans a lab in which students react magnesium ribbon with hydrochloric acid to study reaction rate. The draft procedure has each group use 'a piece of magnesium' and 'about 20 mL of 3 M HCl,' time the reaction until the metal disappears, and compare room-temperature and warm-water trials.
622 words, about 3 min