Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 253 · 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: reading the message is a job a child can do. (a) False (b) True
2. 2.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
3. 3.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
4. 4.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
5. 5.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) cutting the lemon (d) plugging in the iron
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) a cotton bud (d) a small bowl
8. 8.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) writing turns green (d) the paper floats
9. 9.True or false: writing the message is a job a child can do. (a) True (b) False
10. 10.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
11. 11.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a balloon (c) a battery cell (d) a mirror
13. 13.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) yes, in the dark (d) no, it stays brown
14. 14.⚖️ 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 keep it the same (c) we measure it
15. 15.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) a balloon
17. 17.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) dipping the cotton bud
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) a battery cell
19. 19.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
20. 20.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
21. 21.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a mirror (c) yeast (d) a battery cell
22. 22.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
23. 23.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) cutting the lemon
24. 24.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) putting the iron away
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
26. 26.True or false: plugging in the iron is a job for an adult. (a) False (b) True
27. 27.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
28. 28.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
29. 29.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a mirror (d) an adult with an iron
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) how dark the writing is (c) the kind of juice (d) the same cotton bud
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) turmeric powder (d) a cotton bud
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) white paper (d) a mirror
33. 33.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) dipping the cotton bud (c) reading the message (d) writing the message
34. 34.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) reading the message
35. 35.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
36. 36.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) writing the message (d) ironing the paper
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
38. 38.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
39. 39.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) cutting the lemon (d) putting the iron away
40. 40.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True

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