Lesson 20 · Annual review

Mia's Math Expedition

Twelve stations from the whole year. Find what is solid and what deserves another look.

Treat this like an expedition, not a test. Work without opening the answers. If a station feels foggy, write what you know and move on. An honest question mark gives us useful information.

Four regions of the annual reviewA path connects algebra, patterns, shapes, and change.ALGEBRAPATTERNSSHAPESCHANGEequationssequencesgeometryrates + lines
Read preciselyDraw a modelShow the equationAttach units
Worked example: show enough thinking

Three sketchbooks cost €4 each and one pencil costs €2. Model: $3\times4+2$. Calculate: $12+2=14$. Conclusion: the total is €14.

Region 1: Algebra
  1. Station 1: Build and solve an equation

    Mia has $5$ kg of hay. She buys $x$ bags of $\frac23$ kg each and finishes with $17$ kg.

    1. Write an equation.
    2. Solve for $x$, showing each operation on both sides.
    3. Check by substitution.
    equation → equivalent operations → check →
  2. Station 2: Negative-coefficient inequality

    A tank starts at $18$ L and loses $3$ L each hour. Let $h=$ elapsed hours. Find when it contains at most $6$ L.

    1. Write an inequality.
    2. Solve it and show where the sign reverses.
    3. Interpret the solution beginning, “After at least...”
    model → isolate → divide by a negative → interpret →
Region 2: Patterns and proportion
  1. Station 3: Arithmetic sequence

    A plan decreases the number of jumps each day: $72,65,58,51,\ldots$

    1. Calculate $d$.
    2. Write an explicit formula for $a_n$.
    3. Calculate $a_{10}$.
    difference → formula → substitute →
  2. Station 4: Geometric sequence

    An image is repeatedly compressed: $640,320,160,80,\ldots$ kilobytes.

    1. Calculate $r$.
    2. Write an explicit formula.
    3. Calculate $a_7$.
    ratio → formula → substitute →
  3. Station 5: Inverse proportion

    A fixed hay supply feeds $4$ horses for $15$ days.

    1. Choose DIRECT or INVERSE proportion.
    2. Calculate the constant horse-days.
    3. Calculate how long it feeds $6$ horses.
    relationship → constant product → days →
Region 3: Shapes and measurement
  1. Station 6: Angle relationships
    68°xy
    1. Calculate $x$ and name the relationship.
    2. Calculate $y$ and name the relationship.
    relationship → equation → calculate →
  2. Station 7: Triangle congruence
    BACEDF6 cm8 cm6 cm8 cm45°45°
    1. Choose SSS, SAS, ASA, AAS, or not enough information.
    2. Match vertices $A,B,C$ with $D,E,F$.
    3. Name the side corresponding to $BC$.
    matching marks → rule → corresponding parts →
  3. Station 8: Similar triangles
    6 m4 m15 mx
    1. Write a proportion.
    2. Calculate $x$.
    3. Calculate the scale factor from small to large.
    match sides → proportion → solve → scale factor →
  4. Station 9: Area and perimeter
    12 m8 m4 m3 mremoved
    1. Calculate the L-shape's area.
    2. Calculate its perimeter by tracing the outside.
    3. Calculate fencing cost at €7.50/m.
    outer - removed → trace → cost →
Region 4: Change, graphs, and money
  1. Station 10: Slope and rate

    A battery graph uses $x=$ hours and $y=$ battery level in percent. It passes through $(2,84)$ and $(6,60)$.

    1. Choose INCREASES or DECREASES.
    2. Calculate $\Delta y$ in percentage points.
    3. Calculate $\Delta x$ in hours.
    4. Calculate the slope with units.
    5. Interpret the rate in a sentence.
    6. Answer YES or NO: convert it to a percentage gradient? Explain.
    direction → Δy → Δx → divide → units → meaning →
  2. Station 11: Simple interest

    Mia deposits €800 at $3\%$ simple interest per year for $2.5$ years.

    1. Convert the rate to a decimal.
    2. Calculate interest using $I=Prt$.
    3. Calculate the total amount.
    decimal → interest → total →
  3. Station 12: Linear equation

    An art account starts with €40 and grows by €6 each week. Let $x=$ weeks and $y=$ euros.

    1. State $m$ with units.
    2. State $b$ with units.
    3. Write $y=mx+b$.
    4. Calculate the balance after $8$ weeks.
    5. Write the coordinate point for part (d).
    rate → start → equation → substitute → point →
Show answers only after every station
Station 1a
$5+\frac23x=17$.
Station 1b
$$5+\frac23x=17\quad\mid-5$$$$\frac23x=12\quad\mid\times\frac32$$$$x=18$$
Station 1c
$5+\frac23(18)=17$.
Station 2a
$18-3h\leq6$.
Station 2b
$$18-3h\leq6\quad\mid-18$$$$-3h\leq-12\quad\mid\div(-3)$$$$h\geq4$$The sign reverses when dividing by $-3$.
Station 2c
After at least $4$ hours, the tank contains at most $6$ L.
Station 3a
$d=-7$.
Station 3b
$a_n=72+(n-1)(-7)=79-7n$.
Station 3c
$a_{10}=72+9(-7)=9$.
Station 4a
$r=\frac12$.
Station 4b
$a_n=640(\frac12)^{n-1}$.
Station 4c
$a_7=10$ KB.
Station 5a
INVERSE.
Station 5b
$4\times15=60$ horse-days.
Station 5c
$60\div6=10$ days.
Station 6a
$x=68^\circ$, vertically opposite angles.
Station 6b
$y=180^\circ-68^\circ=112^\circ$, supplementary adjacent angles.
Station 7a
SAS.
Station 7b
$A\leftrightarrow D$, $B\leftrightarrow E$, $C\leftrightarrow F$.
Station 7c
$BC$ corresponds to $EF$.
Station 8a
$\frac{x}{4}=\frac{15}{6}$.
Station 8b
$6x=60$, so $x=10$ m.
Station 8c
Scale factor $=15\div6=2.5$.
Station 9a
$A=12\times8-4\times3=84$ m².
Station 9b
$P=8+3+4+5+12+8=40$ m.
Station 9c
$40\times€7.50=€300$.
Station 10a
DECREASES.
Station 10b
$\Delta y=60-84=-24$ percentage points.
Station 10c
$\Delta x=6-2=4$ hours.
Station 10d
$m=-24\div4=-6$ percentage points/hour.
Station 10e
Battery level decreases by $6$ percentage points per hour.
Station 10f
NO. Battery percentage and time are different quantities, so this is not a physical percentage gradient.
Station 11a
$3\%=0.03$.
Station 11b
$I=800\times0.03\times2.5=€60$.
Station 11c
$800+60=€860$.
Station 12a
$m=€6$/week.
Station 12b
$b=€40$.
Station 12c
$y=6x+40$.
Station 12d
$y=6(8)+40=€88$.
Station 12e
$(8,88)$.
Parent review guide

Mark every subpart separately. One isolated miss earns later review; two misses in one skill indicate a remediation pattern. Do not coach on the first pass. Record where clarification is requested, since vocabulary can be a separate blind spot.

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