Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 710 · 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.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
2. 2.True or false: plugging in the iron is a job a child can do. (a) False (b) True
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) a cotton bud (d) a small bowl
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) turmeric powder (d) a small bowl
5. 5.⚖️ 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
6. 6.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
7. 7.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
8. 8.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
9. 9.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the iron setting (c) the kind of juice (d) the same cotton bud
11. 11.True or false: writing the message is a job for an adult. (a) True (b) False
12. 12.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
13. 13.⚖️ 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 change it (c) we measure it
14. 14.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
15. 15.True or false: plugging in the iron is a job for an adult. (a) False (b) True
16. 16.True or false: white paper is needed for the secret lemon message. (a) True (b) False
17. 17.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) writing turns green (d) it gets darker
18. 18.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
19. 19.True or false: ironing the paper is a job a child can do. (a) True (b) False
20. 20.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not 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) a cotton bud (c) a battery cell (d) lemon juice
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a mirror (d) a cotton bud
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) an adult with an iron (d) a cotton bud
24. 24.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
25. 25.True or false: ironing the paper is a job for an adult. (a) True (b) False
26. 26.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
27. 27.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) a magnet (d) a balloon
29. 29.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
30. 30.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is sticky (d) it is cold
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
32. 32.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) ironing the paper (d) cutting the lemon
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
34. 34.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) ironing the paper (d) letting the paper dry
35. 35.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
36. 36.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) letting the paper dry
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
38. 38.True or false: putting the iron away is a job a child can do. (a) False (b) True
39. 39.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) putting the iron away (d) letting the paper dry
40. 40.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True

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