Times-Table Challenge IV

Review — where we got to 5 min

• A streak grows on each right answer, and change [score v] by (streak) makes it pay.
• The level, chosen first, sets min and max.
• The question maker builds question and correct together.

Quick-fire

In the Quiz Show, the green flag set best to 0. What happens to your best score when you close Scratch and open the project tomorrow?

Today’s Topic 3 min

• Easy and Hard buttons: when this sprite clicked, then broadcast [start round v]
• best easy and best hard — records the flag never wipes
• A results card: an if / else chain, highest score first
• (join (words) (join [ You scored ] (score))) — words and numbers in one sentence

Learning outcome

By the end of this lesson you will be able to:

1. Start a game from buttons, with a broadcast.
2. Keep a best score for each level that survives the green flag.
3. Tell the player how they did in words, not just a number.

Learnt — menu, record, card 28 min

1 · A menu with two buttons

Typing “easy” works, but a button is quicker and nobody spells it wrong. You made a Start button in the Quiz Show. Today there are two, and each one means something.

1. Add the Button2 sprite. Name it Easy.
2. In the Costumes tab, pick the T tool and write Easy on it.
3. Right-click the sprite and Duplicate it. Name the copy Hard and change its word.
4. Make a variable called level.
5. Give each button the three scripts below.

when this sprite clicked
set [level v] to [easy]
broadcast [start round v]
              

when I receive [start round v]
hide
              

when I receive [menu v]
show
              

The Hard button is the same, with hard in its set block. The Wizard hears the message and reads level:

when flag clicked
broadcast [menu v]

when I receive [menu v]
say [Pick Easy or Hard.]
              

when I receive [start round v]
if <(level) = [easy]> then
  say [Easy: numbers 1 to 5.] for (3) seconds
else
  say [Hard: numbers 2 to 12.] for (3) seconds
end
broadcast [menu v]
              

2 · A best score the flag never wipes

In the Quiz Show, the flag set best to 0. So the best only lasted until the next flag. Today’s rule is simple:

Scratch saves every variable’s number inside the project. So a best that nothing resets is still there tomorrow.

1. Make best easy and best hard. Good names — not b1 and b2.
2. Drag out set [best easy v] to (0) on its own. Do not join it to any hat.
3. Click it once. Do the same for best hard.
4. Delete the two loose blocks. The bests now start at 0.
5. Save the project.

when flag clicked
set [score v] to (pick random (10) to (40))
say (join [This round: ] (score)) for (2) seconds
if <(score) > (best easy)> then
  set [best easy v] to (score)
  say [A new best!] for (2) seconds
else
  say (join [Best is still ] (best easy)) for (2) seconds
end
            

One best for each level

20 on hard is harder than 40 on easy. One best for both would be unfair. So the round checks the level first:

when I receive [round over v]
if <(level) = [easy]> then
  if <(score) > (best easy)> then
    set [best easy v] to (score)
  end
else
  if <(score) > (best hard)> then
    set [best hard v] to (score)
  end
end
broadcast [results card v]
            

3 · A result in words

“You scored 57” means little to a new player. “Great work!” means something straight away. The words depend on the score.

when I receive [results card v]
if <(score) > (99)> then
  set [words v] to [Times-table master!]
else
  if <(score) > (39)> then
    set [words v] to [Great work!]
  else
    if <(score) > (9)> then
      set [words v] to [Good start.]
    else
      set [words v] to [Keep practising.]
    end
  end
end
say (join (words) (join [ You scored ] (score))) for (3) seconds
            

when flag clicked
set [score v] to (3)
broadcast [results card v] and wait
set [score v] to (25)
broadcast [results card v] and wait
set [score v] to (60)
broadcast [results card v] and wait
set [score v] to (130)
broadcast [results card v] and wait
            

Why such big numbers? The streak. Twenty right in a row on easy is 1 + 2 + … + 20, which is 210.

Basic — finish the game 25 min

Open last lesson’s game. By the end the Wizard has seven scripts. Test after each step.

Step 1 — the buttons

1. Make the Easy and Hard buttons from Learnt 1, with all three scripts each.
2. Drag them onto the chalkboard, one above the other.

Step 2 — the flag and the menu

1. Pull the ask and the level if / else off the flag script. Keep them to one side.
2. The flag script becomes broadcast [menu v] and nothing else.
3. Add a when I receive [menu v] script. It switches to the Chalkboard and says “Pick Easy or Hard.”

Step 3 — start round

1. Start a when I receive [start round v] script.
2. Put the level if / else under it, testing (level), not (answer).
3. Then set score, streak and lives, and broadcast play.

Step 4 — round over

1. In the play script, change the last say to broadcast [round over v].
2. Build the round over script from Learnt 2.
3. Build the results card script from Learnt 3.
4. At the end of the card, say it with the level too, then broadcast [menu v].

Step 5 — the bests

1. Click a loose set-to-0 block once for each best, then delete it.
2. Play easy twice and hard once.
3. Press the green flag. Both bests must still be there.

when flag clicked
broadcast [menu v]

when I receive [menu v]
switch backdrop to [Chalkboard v]
say [Pick Easy or Hard.]

when I receive [start round v]
say []
if <(level) = [hard]> then
  set [min v] to (2)
  set [max v] to (12)
else
  set [min v] to (1)
  set [max v] to (5)
end
set [score v] to (0)
set [streak v] to (0)
set [lives v] to (3)
broadcast [play v]
              

when I receive [results card v]
switch backdrop to [Spotlight v]
if <(score) > (99)> then
  set [words v] to [Times-table master!]
else
  if <(score) > (39)> then
    set [words v] to [Great work!]
  else
    if <(score) > (9)> then
      set [words v] to [Good start.]
    else
      set [words v] to [Keep practising.]
    end
  end
end
say (join (words) (join [ You scored ] (join (score) (join [ on ] (level))))) for (5) seconds
broadcast [menu v]
              

The play script is last lesson’s, ending in broadcast [round over v]. The question maker and the clock do not change.

A record moment

Beating a best is a big deal. Make the game say so.

• When a best is beaten, the Wizard says “New best on easy!” or “New best on hard!”.
• It happens before the results card.
• A round that does not beat the best says nothing extra.

if <(score) > (best hard)> then
  set [best hard v] to (score)
  say (join [New best on ] (join (level) [!])) for (2) seconds
end
            

Your own words

Rewrite the results card in your own words, with more steps.

• At least five different cards.
• Every card still shows the score.
• The tests go from the highest score down.

A Medium button

Add a third level, with its own button and its own best.

• A Medium button between Easy and Hard.
• Medium uses numbers from 2 to 9.
• A best medium that only a medium round can change.
• The card names the level, whichever it was.

if <(level) = [easy]> then
  if <(score) > (best easy)> then
    set [best easy v] to (score)
  end
else
  if <(level) = [medium]> then
    if <(score) > (best medium)> then
      set [best medium v] to (score)
    end
  else
    if <(score) > (best hard)> then
      set [best hard v] to (score)
    end
  end
end
            

Wipe the records, safely

Sometimes a player wants a fresh start. Let them wipe the bests — but never by accident.

• On the menu, pressing R asks “Type YES to wipe the best scores.”
• Only YES wipes them. Anything else leaves them alone.
• R does nothing during a round.

when [r v] key pressed
if <(on menu) = [yes]> then
  ask [Type YES to wipe the best scores.] and wait
  if <(answer) = [YES]> then
    set [best easy v] to (0)
    set [best hard v] to (0)
    say [Records wiped.] for (2) seconds
  else
    say [Records kept.] for (2) seconds
  end
end
            

Summary 5 min

The Times-Table Challenge is finished. Over four lessons it learnt to:

1. make up its own questions with pick random, join and the green maths blocks;
2. run against a clock, with lives, and end by itself;
3. reward a streak, change its level, and mix × and +;
4. start from a menu, keep a best for each level, and give a result in words.

Today’s big idea: some variables are reset every round, and some are never reset by the flag at all. Choosing which is which is part of designing a game.

Menu

The first screen. The player chooses there, then the game starts.

Best score

The highest score so far. It only changes when it is beaten.

Saved value

The number a variable held when you saved. It comes back when you open the file.

Results card

The end screen that tells the player how they did, in words.

Hand in

Save your finished game. If you have a Scratch account, share it and send the link to your teacher. Then play it cold tomorrow: can you follow it with every script window shut?

Next lesson: a new arc — Road Crossing. Lanes of cars, and a hopper that has to get across.