Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 769 · 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: plugging in the iron is a job for an adult. (a) False (b) True
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) turmeric powder
3. 3.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
4. 4.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
5. 5.True or false: writing the message is a job a child can do. (a) True (b) False
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a balloon (d) lemon juice
7. 7.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same paper
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
10. 10.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
11. 11.⚖️ 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
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) a small bowl (d) lemon juice
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the ironing time
14. 14.🍋 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) cutting the lemon
15. 15.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
16. 16.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) a mirror (d) turmeric powder
17. 17.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) ironing the paper (d) reading the message
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
19. 19.🍋 Which of these steps is a job for an adult? (a) reading the message (b) putting the iron away (c) letting the paper dry (d) dipping the cotton bud
20. 20.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
21. 21.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
22. 22.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
23. 23.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
26. 26.⚖️ 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 measure it (c) we keep it the same
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the ironing time
28. 28.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
29. 29.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
30. 30.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
31. 31.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) magnetic (d) musical
32. 32.True or false: reading the message is a job a child can do. (a) False (b) True
33. 33.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
34. 34.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
35. 35.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
36. 36.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the ironing time (d) the iron setting
38. 38.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) reading the message
39. 39.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) it gets darker (d) writing turns green
40. 40.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it

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