Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 563 · 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 is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
2. 2.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
3. 3.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) ironing the paper (d) cutting the lemon
4. 4.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
5. 5.True or false: putting the iron away is a job a child can do. (a) False (b) True
6. 6.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
7. 7.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) letting the paper dry (d) writing the message
8. 8.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
9. 9.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) writing the message
10. 10.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
11. 11.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
12. 12.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
13. 13.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same cotton bud (c) the kind of juice
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a battery cell (d) a small bowl
16. 16.⚖️ 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
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
18. 18.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
19. 19.True or false: yeast is needed for the secret lemon message. (a) True (b) False
20. 20.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
21. 21.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
23. 23.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
24. 24.True or false: ironing the paper is a job for an adult. (a) True (b) False
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) a small bowl (d) a cotton bud
26. 26.🔮 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
27. 27.True or false: letting the paper dry is a job a child can do. (a) False (b) True
28. 28.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
29. 29.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
30. 30.True or false: white paper is needed for the secret lemon message. (a) False (b) True
31. 31.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
32. 32.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
33. 33.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
34. 34.⚖️ 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
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) lemon juice (c) an adult with an iron (d) a cotton bud
36. 36.🧺 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) a cotton bud (d) a mirror
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) white paper (d) turmeric powder
39. 39.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
40. 40.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical

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