Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 141 · 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.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
2. 2.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) reading the message (c) plugging in the iron (d) ironing the paper
3. 3.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) a mirror (d) a cotton bud
4. 4.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is magnetic (d) it is cold
5. 5.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
6. 6.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
7. 7.True or false: cutting the lemon is a job a child can do. (a) True (b) False
8. 8.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a magnet (d) a cotton bud
10. 10.🍋 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
11. 11.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) a magnet (d) a mirror
12. 12.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) an adult with an iron (d) a balloon
14. 14.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
15. 15.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) ironing the paper (d) putting the iron away
16. 16.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
17. 17.True or false: letting the paper dry is a job for an adult. (a) True (b) False
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) white paper (d) a small bowl
19. 19.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, in the dark (d) yes, if shaken
20. 20.⚖️ 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
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) white paper (d) a small bowl
22. 22.True or false: letting the paper dry is a job a child can do. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
24. 24.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) a battery cell
28. 28.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) physical (d) magnetic
29. 29.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
30. 30.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) ironing the paper (d) cutting the lemon
31. 31.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
33. 33.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) writing the message (d) dipping the cotton bud
34. 34.True or false: putting the iron away is a job a child can do. (a) True (b) False
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
36. 36.🛟 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
37. 37.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) reading the message
38. 38.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) plugging in the iron
39. 39.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
40. 40.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) letting the paper dry (d) plugging in the iron

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