Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 22 · 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: a mirror is not needed for the secret lemon message. (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) an adult with an iron (c) lemon juice (d) a mirror
3. 3.⚖️ 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
4. 4.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
5. 5.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
6. 6.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the kind of juice (c) the ironing time (d) how dark the writing is
8. 8.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
10. 10.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
11. 11.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) letting the paper dry (d) writing the message
12. 12.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) lemon juice (d) a balloon
14. 14.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
15. 15.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a battery cell (d) a cotton bud
18. 18.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) writing the message (d) letting the paper dry
19. 19.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
20. 20.True or false: letting the paper dry is a job a child can do. (a) True (b) False
21. 21.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) plugging in the iron (d) putting the iron away
22. 22.True or false: white paper is needed for the secret lemon message. (a) True (b) False
23. 23.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a mirror (d) an adult with an iron
25. 25.⚖️ 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
26. 26.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) reading the message (d) letting the paper dry
27. 27.True or false: ironing the paper is a job for an adult. (a) False (b) True
28. 28.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
29. 29.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
30. 30.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
31. 31.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
32. 32.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
33. 33.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
34. 34.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
35. 35.True or false: putting the iron away is a job a child can do. (a) True (b) False
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a small bowl (c) white paper (d) a cotton bud
38. 38.True or false: cutting the lemon is a job a child can do. (a) True (b) False
39. 39.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) dipping the cotton bud (c) ironing the paper (d) cutting the lemon
40. 40.⚖️ 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) the iron setting (c) how dark the writing is

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