Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 797 · 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) lemon juice (b) an adult with an iron (c) a small bowl (d) turmeric powder
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
3. 3.True or false: reading the message is a job a child can do. (a) True (b) False
4. 4.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
5. 5.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
6. 6.True or false: putting the iron away is a job for an adult. (a) False (b) True
7. 7.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
8. 8.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) plugging in the iron (d) putting the iron away
9. 9.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
10. 10.🛟 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
11. 11.True or false: ironing the paper is a job for an adult. (a) False (b) True
12. 12.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a magnet (d) a small bowl
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the same paper (c) the kind of juice (d) the same cotton bud
15. 15.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a small bowl (d) a battery cell
16. 16.🍋 Which of these steps is a job for an adult? (a) reading the message (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
17. 17.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
18. 18.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
19. 19.⚖️ 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
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the ironing time (c) how dark the writing is (d) the same paper
21. 21.⚖️ 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
22. 22.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
23. 23.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
24. 24.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) ironing the paper
25. 25.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a magnet (d) an adult with an iron
27. 27.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) putting the iron away (d) writing the message
28. 28.⚖️ 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
29. 29.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
30. 30.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
31. 31.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) plugging in the iron
32. 32.True or false: ironing the paper is a job a child can do. (a) True (b) False
33. 33.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a balloon (d) white paper
35. 35.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
36. 36.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
37. 37.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
38. 38.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the juice scorches first (d) the iron is brown
39. 39.⚖️ 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 keep it the same (c) we measure it
40. 40.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True

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