Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 700 · 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 of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) cutting the lemon (d) plugging in the iron
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
3. 3.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) reading the message (d) writing the message
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 change it (b) we measure it (c) we keep it the same
5. 5.🍋 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
6. 6.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) lemon juice (d) white paper
8. 8.True or false: putting the iron away is a job for an adult. (a) False (b) True
9. 9.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) white paper (d) an adult with an iron
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
12. 12.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
13. 13.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
14. 14.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
15. 15.⚖️ 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
16. 16.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) letting the paper dry (d) writing the message
17. 17.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
19. 19.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) yeast (d) a battery cell
21. 21.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
22. 22.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
23. 23.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) lemon juice (d) a magnet
24. 24.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
25. 25.True or false: plugging in the iron is a job a child can do. (a) True (b) False
26. 26.True or false: yeast is needed for the secret lemon message. (a) True (b) False
27. 27.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
28. 28.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
29. 29.True or false: cutting the lemon is a job for an adult. (a) False (b) True
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
31. 31.⚖️ 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 same cotton bud (d) the kind of juice
32. 32.🛟 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
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) white paper (d) a mirror
34. 34.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a small bowl (d) a magnet
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) white paper (c) a mirror (d) a battery cell
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a battery cell (d) lemon juice
37. 37.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
38. 38.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the ironing time (c) the same cotton bud (d) how dark the writing is

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