Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 17 · 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 a balloon for the secret lemon message? (a) needed (b) not needed
2. 2.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) lemon juice (c) a small bowl (d) white paper
4. 4.⚖️ 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 keep it the same (c) we change it
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) an adult with an iron (d) a magnet
7. 7.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
8. 8.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) yeast (c) white paper (d) lemon juice
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
11. 11.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the ironing time (c) the same cotton bud (d) the kind of juice
13. 13.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
14. 14.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
16. 16.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
17. 17.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) a magnet (d) a balloon
18. 18.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) letting the paper dry (d) writing the message
19. 19.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a mirror
21. 21.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) reading the message (d) letting the paper dry
22. 22.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
23. 23.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
24. 24.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
25. 25.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
27. 27.True or false: cutting the lemon is a job for an adult. (a) False (b) True
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) lemon juice (d) a cotton bud
29. 29.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a balloon (d) a cotton bud
31. 31.True or false: letting the paper dry is a job for an adult. (a) True (b) False
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) lemon juice (d) a balloon
34. 34.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) ironing the paper (d) letting the paper dry
35. 35.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
36. 36.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a magnet (d) a balloon
37. 37.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) an adult with an iron (d) a small bowl
39. 39.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) a small bowl (d) lemon juice

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