Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 163 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
2. 2.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
3. 3.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) the iron is brown (d) paper turns lemony
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) the iron setting (d) the ironing time
6. 6.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
8. 8.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
9. 9.True or false: plugging in the iron is a job for an adult. (a) True (b) False
10. 10.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a magnet (c) turmeric powder (d) a battery cell
11. 11.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
12. 12.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) white paper (c) a small bowl (d) lemon juice
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice
18. 18.True or false: writing the message is a job for an adult. (a) True (b) False
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a battery cell (d) lemon juice
21. 21.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
22. 22.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
23. 23.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) ironing the paper (d) letting the paper dry
24. 24.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
26. 26.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) reading the message (d) plugging in the iron
27. 27.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) writing the message (d) plugging in the iron
28. 28.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
29. 29.True or false: cutting the lemon is a job a child can do. (a) False (b) True
30. 30.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
31. 31.True or false: white paper is needed for the secret lemon message. (a) True (b) False
32. 32.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
34. 34.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) reading the message (d) plugging in the iron
35. 35.True or false: cutting the lemon is a job for an adult. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
37. 37.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
38. 38.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) a battery cell (d) an adult with an iron
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) yeast

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