Lesson Plan

• Describe the mole as a counting unit and state the value of Avogadro’s constant.
• Apply the equation $n = \dfrac{m}{M}$ to convert between mass and amount of substance.
• Calculate molar mass from periodic‑table data and use it in calculations.
• Convert moles to number of particles using $N_{\text A}$ and vice‑versa.
• Identify and avoid common pitfalls such as confusing molar mass with relative atomic mass and mishandling significant figures.

• Projector or interactive whiteboard
• Periodic‑table handouts
• Worksheet with practice conversion problems
• Scientific calculators
• Whiteboard and markers
• Sample of NaCl and a balance (optional demonstration)

Begin by asking students how many atoms might be in a spoonful of sugar to spark curiosity about counting huge numbers of particles. Review that atomic mass units relate to grams via the mole concept. Explain that by the end of the lesson they will be able to convert mass ↔ moles accurately and state the success criteria for the day.

1. Do‑Now (5'): Quick mental question – “If 1 mol of carbon atoms weighs 12 g, how many grams are 0.5 mol?” Collect answers.
2. Mini‑lecture (10'): Define the mole, Avogadro constant, and derive $n = m/M$ with examples.
3. Guided practice (15'): Work through Worked Example 1 (mass → moles) on the board, prompting student input.
4. Partner activity (10'): Students calculate molar masses from the periodic‑table handout and solve Worked Example 2 (moles → mass).
5. Concept check (5'): Exit‑ticket question – convert 3.00 g of H₂O to moles and then to number of molecules.
6. Reflection & recap (5'): Discuss common pitfalls and answer any lingering questions.

Summarise that the mole links the microscopic and macroscopic worlds via $n = m/M$ and $N_{\text A}$. Students complete an exit ticket converting a given mass to moles and particles, demonstrating mastery. For homework, assign the worksheet’s additional practice questions to reinforce the conversions.