Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 447 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the paper ate it (d) the ink is magnetic
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) an adult with an iron (d) a cotton bud
3. 3.True or false: plugging in the iron is a job for an adult. (a) False (b) True
4. 4.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) ironing the paper (d) putting the iron away
5. 5.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) ironing the paper
6. 6.⚖️ 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
7. 7.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a balloon (d) white paper
8. 8.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) reading the message
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
10. 10.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
11. 11.⚖️ 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
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same paper (c) the ironing time (d) the kind of juice
13. 13.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
14. 14.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
15. 15.🍋 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) dipping the cotton bud
16. 16.⚖️ 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
17. 17.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
18. 18.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) lemon juice (d) a magnet
19. 19.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
20. 20.🧺 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) yeast (d) a cotton bud
21. 21.⚖️ 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
22. 22.🔮 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
23. 23.True or false: cutting the lemon is a job for an adult. (a) True (b) False
24. 24.⚖️ 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
25. 25.⚖️ 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 measure it (c) we change it
26. 26.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
27. 27.True or false: yeast is needed for the secret lemon message. (a) True (b) False
28. 28.⚖️ 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 cotton bud
29. 29.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
30. 30.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) an adult with an iron (c) a small bowl (d) lemon juice
32. 32.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) letting the paper dry (d) reading the message
33. 33.⚖️ 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 keep it the same (c) we measure it
34. 34.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
35. 35.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) dipping the cotton bud
36. 36.🧺 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 balloon (d) lemon juice
37. 37.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) blue (d) white
38. 38.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) plugging in the iron
39. 39.True or false: putting the iron away is a job a child can do. (a) False (b) True
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a magnet (d) a cotton bud

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