Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 532 · 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 is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) white paper (d) a battery cell
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a small bowl (d) a mirror
3. 3.⚖️ 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 kind of juice (c) how dark the writing is (d) the ironing time
4. 4.True or false: ironing the paper is a job for an adult. (a) True (b) False
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
6. 6.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) putting the iron away (d) cutting the lemon
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) any child (d) whoever is fastest
9. 9.True or false: cutting the lemon is a job for an adult. (a) True (b) False
10. 10.🍋 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
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a magnet (d) a cotton bud
12. 12.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) a rainbow (d) dark brown words
13. 13.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
14. 14.⚖️ 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
15. 15.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) cutting the lemon (d) writing the message
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a balloon (c) a small bowl (d) lemon juice
17. 17.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
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) False (b) True
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) yeast (c) a battery cell (d) a mirror
20. 20.⚖️ 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) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) turmeric powder (d) lemon juice
23. 23.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) lemon juice (d) a cotton bud
25. 25.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) writing the message
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) turmeric powder (d) white paper
27. 27.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
28. 28.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) putting the iron away
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a small bowl (d) lemon juice
30. 30.🛟 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
31. 31.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
32. 32.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) an adult with an iron (d) turmeric powder
33. 33.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
34. 34.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) white paper (d) a balloon
35. 35.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
36. 36.⚖️ 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
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
38. 38.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) white paper (d) a mirror
40. 40.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) cutting the lemon (d) putting the iron away

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