Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 427 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
2. 2.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is magnetic (d) it is cold
3. 3.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
4. 4.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
6. 6.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
7. 7.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) yeast (d) a small bowl
9. 9.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
10. 10.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
12. 12.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) reading the message (d) dipping the cotton bud
13. 13.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
14. 14.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
15. 15.🧺 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 balloon (d) a small bowl
16. 16.⚖️ 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) False (b) True
17. 17.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) an adult with an iron (d) lemon juice
20. 20.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
21. 21.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a magnet (d) a small bowl
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) turmeric powder (d) a cotton bud
24. 24.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) putting the iron away (d) reading the message
25. 25.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
27. 27.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
28. 28.True or false: cutting the lemon is a job a child can do. (a) True (b) False
29. 29.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
30. 30.True or false: putting the iron away is a job for an adult. (a) True (b) False
31. 31.⚖️ 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 measure it (c) we keep it the same
32. 32.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) turmeric powder (d) an adult with an iron
34. 34.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) ironing the paper (d) cutting the lemon
35. 35.True or false: ironing the paper is a job a child can do. (a) True (b) False
36. 36.⚖️ 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 measure it (c) we change it
37. 37.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
38. 38.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) a battery cell (d) an adult with an iron

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