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9th grade · Social Studies · Unit 10 of 10

Supply & Demand

Shifts, prices, shortages and surpluses

What your child practices

Practices how buyers and sellers set market prices, what shifts supply and demand, and shortages and surpluses.

Minnesota K-12 Academic Standards benchmark: 9.2.10.4; 9.2.10.5 · supply, demand and market prices

How we explain it

Children can open this short lesson before they practice.

  1. Demand shifts with what buyers want: rain raises demand for umbrellas; a dry summer lowers it.
  2. Supply shifts with costs: costlier milk cuts ice cream supply; faster machines raise bike supply and lower prices.
  3. Price too low: shortage = demand − supply. Price too high: surplus = supply − demand.

Example: At $3, buyers want 80 and sellers offer 30. What happens? Demand is more than supply. 80 − 30 = 50 more wanted than offered. Answer: a shortage of 50

Supply & Demand in Minnesota

In the Minnesota K-12 Academic Standards, this is unit 10 of 10 in 9th grade Social Studies, after How Laws Are Made.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Minnesota Department of Education (MDE)

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    A new ice cream factory opens. What happens in the market for ice cream?

    • demand increases
    • demand decreases
    • supply increases
    • supply decreases

  2. Question 2

    The price of milk and cream doubles. What will most likely happen to the equilibrium price of ice cream?

    • it falls
    • it rises
    • it stays exactly the same

  3. Question 3

    Factories find a cheaper way to make umbrellas. What happens in the market for umbrellas?

    • supply decreases
    • demand decreases
    • supply increases
    • demand increases

  4. Question 4

    A record corn harvest in Minnesota and other states increases the supply of corn. The price of corn will most likely…

    • fall
    • rise
    • become zero
    • stay exactly the same

  5. Question 5

    A city closes its bike lanes. What will most likely happen to the equilibrium price of bicycles?

    • it stays exactly the same
    • it falls
    • it rises

  6. Question 6

    Use the table. If the price is set at $4, what happens?

    Market for a good
    PriceQuantity demandedQuantity supplied
    $318030
    $416060
    $514090
    $6120120
    $7100150
    $880180
    • a surplus of 100
    • a shortage of 100
    • a shortage of 160
    • no shortage or surplus

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