Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 270 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a cotton bud (c) a small bowl (d) lemon juice
2. 2.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
3. 3.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) cutting the lemon (d) putting the iron away
4. 4.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
5. 5.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
6. 6.🍋 Which of these steps is a job a child can do? (a) reading the message (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
8. 8.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) a cotton bud (d) white paper
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a balloon
11. 11.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
12. 12.True or false: letting the paper dry is a job for an adult. (a) True (b) False
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the ironing time (d) the same cotton bud
14. 14.⚖️ 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
15. 15.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
16. 16.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
17. 17.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
18. 18.⚖️ 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
19. 19.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
20. 20.⚖️ 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
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a mirror (d) a small bowl
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) a balloon (d) lemon juice
23. 23.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a battery cell (d) a cotton bud
25. 25.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) letting the paper dry (d) cutting the lemon
26. 26.True or false: yeast is needed for the secret lemon message. (a) False (b) True
27. 27.⚖️ 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 ironing time (c) the iron setting (d) the kind of juice
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a mirror (d) lemon juice
29. 29.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
31. 31.⚖️ 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
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
34. 34.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) a battery cell
36. 36.True or false: writing the message is a job for an adult. (a) False (b) True
37. 37.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) letting the paper dry (d) reading the message
39. 39.⚖️ 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
40. 40.True or false: plugging in the iron is a job for an adult. (a) False (b) True

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