Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 234 · 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.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
2. 2.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
3. 3.True or false: letting the paper dry is a job for an adult. (a) False (b) True
4. 4.⚖️ 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) how dark the writing is (d) the iron setting
5. 5.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
6. 6.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
8. 8.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) writing the message
9. 9.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
10. 10.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
11. 11.True or false: writing the message is a job a child can do. (a) True (b) False
12. 12.⚖️ 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 measure it (c) we keep it the same
13. 13.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) putting the iron away (d) letting the paper dry
14. 14.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) cutting the lemon (d) putting the iron away
15. 15.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) white paper (c) lemon juice (d) a small bowl
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
18. 18.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) yeast (d) a magnet
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a mirror (d) lemon juice
20. 20.⚖️ 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
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic
22. 22.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
23. 23.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
24. 24.True or false: putting the iron away is a job for an adult. (a) False (b) True
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) turmeric powder (d) a magnet
26. 26.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
27. 27.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a magnet (d) white paper
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) turmeric powder (d) lemon juice
31. 31.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
32. 32.⚖️ 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
33. 33.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
34. 34.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
35. 35.True or false: ironing the paper is a job for an adult. (a) False (b) True
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a cotton bud (d) a mirror
37. 37.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
38. 38.True or false: letting the paper dry is a job a child can do. (a) False (b) True
39. 39.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
40. 40.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) putting the iron away (c) cutting the lemon (d) ironing the paper

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