Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 527 · 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.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) writing the message (d) cutting the lemon
2. 2.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
3. 3.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
4. 4.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is sticky (d) it is cold
5. 5.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
8. 8.⚖️ 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
9. 9.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) reading the message
10. 10.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
11. 11.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
12. 12.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
13. 13.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) reading the message (d) dipping the cotton bud
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
15. 15.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) white paper (c) a cotton bud (d) a small bowl
17. 17.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) blue (d) white
18. 18.🛟 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
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a small bowl (d) yeast
20. 20.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a balloon (d) lemon juice
22. 22.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
23. 23.True or false: ironing the paper is a job a child can do. (a) False (b) True
24. 24.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is (d) the ironing time
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
27. 27.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) a balloon (d) a magnet
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) lemon juice (d) turmeric powder
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
30. 30.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
31. 31.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
33. 33.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) ironing the paper
34. 34.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
35. 35.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
36. 36.⚖️ 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
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) turmeric powder
38. 38.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
39. 39.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) cutting the lemon (d) plugging in the iron
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it

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