Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 223 · 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: yeast is not needed for the secret lemon message. (a) True (b) False
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
3. 3.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
4. 4.🛟 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
5. 5.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
6. 6.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) writing the message (d) dipping the cotton bud
7. 7.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a battery cell (d) a small bowl
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
11. 11.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) a balloon (d) lemon juice
13. 13.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
14. 14.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the same cotton bud (c) the iron setting (d) how dark the writing is
16. 16.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) a magnet (d) a balloon
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
18. 18.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) ironing the paper
19. 19.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
20. 20.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the same paper (c) the iron setting (d) the kind of juice
22. 22.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
23. 23.🍋 Which of these steps is a job for an adult? (a) reading the message (b) putting the iron away (c) writing the message (d) letting the paper dry
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
25. 25.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) reading the message (d) putting the iron away
26. 26.True or false: yeast is needed for the secret lemon message. (a) False (b) True
27. 27.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
28. 28.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
29. 29.True or false: letting the paper dry is a job a child can do. (a) False (b) True
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) a cotton bud (d) a small bowl
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
32. 32.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
34. 34.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) an adult with an iron (c) white paper (d) a small bowl
36. 36.⚖️ 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
37. 37.True or false: cutting the lemon is a job for an adult. (a) True (b) False
38. 38.⚖️ 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 iron setting (c) the kind of juice
39. 39.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) letting the paper dry (d) writing the message
40. 40.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed

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