Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 372 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) a small bowl (d) white paper
2. 2.True or false: reading the message is a job for an adult. (a) False (b) True
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a magnet (d) a small bowl
4. 4.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a small bowl (c) turmeric powder (d) a mirror
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) yeast (c) a balloon (d) a magnet
6. 6.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
7. 7.⚖️ 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
8. 8.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
11. 11.True or false: ironing the paper is a job a child can do. (a) False (b) True
12. 12.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
13. 13.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
17. 17.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) plugging in the iron
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a magnet (d) lemon juice
19. 19.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) letting the paper dry
20. 20.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) plugging in the iron
21. 21.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) reading the message (d) plugging in the iron
22. 22.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) turmeric powder (d) a mirror
23. 23.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
24. 24.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
25. 25.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) turmeric powder (d) a cotton bud
27. 27.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
28. 28.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
29. 29.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
30. 30.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) the iron is brown (d) heat adds colour
31. 31.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a mirror (c) a small bowl (d) lemon juice
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
34. 34.True or false: writing the message is a job for an adult. (a) False (b) True
35. 35.🧺 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) a battery cell (d) a cotton bud
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same cotton bud (c) the kind of juice (d) the same paper
37. 37.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the same paper (d) the kind of juice
40. 40.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue

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